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js回调函数原理(教你判断下跌还是回调)

程序员文章站 2023-11-21 18:50:22
1、输入一个值,返回其数据类型**function type(para) {return object.prototype.tostring.call(para)}2、数组去重function uni...

1、输入一个值,返回其数据类型**

function type(para) {

return object.prototype.tostring.call(para)

}

2、数组去重

function unique1(arr) {

return […new set(arr)]

}

function unique2(arr) {

var obj = {};

return arr.filter(ele => {

if (!obj[ele]) {

obj[ele] = true;

return true;

}

})

}

function unique3(arr) {

var result = [];

arr.foreach(ele => {

if (result.indexof(ele) == -1) {

result.push(ele)

}

})

return result;

}

3、字符串去重

string.prototype.unique = function () {

var obj = {},

str = ”,

len = this.length;

for (var i = 0; i < len; i++) {

if (!obj[this[i]]) {

str += this[i];

obj[this[i]] = true;

}

}

return str;

}

###### //去除连续的字符串

function uniq(str) {

return str.replace(/(w)1+/g, ‘$1’)

}

js回调函数原理(教你判断下跌还是回调)

4、深拷贝 浅拷贝

//深克隆(深克隆不考虑函数)

function deepclone(obj, result) {

var result = result || {};

for (var prop in obj) {

if (obj.hasownproperty(prop)) {

if (typeof obj[prop] == ‘object’ && obj[prop] !== null) {

// 引用值(obj/array)且不为null

if (object.prototype.tostring.call(obj[prop]) == ‘[object object]’) {

// 对象

result[prop] = {};

} else {

// 数组

result[prop] = [];

}

deepclone(obj[prop], result[prop])

} else {

// 原始值或func

result[prop] = obj[prop]

}

}

}

return result;

}

// 深浅克隆是针对引用值

function deepclone(target) {

if (typeof (target) !== ‘object’) {

return target;

}

var result;

if (object.prototype.tostring.call(target) == ‘[object array]’) {

// 数组

result = []

} else {

// 对象

result = {};

}

for (var prop in target) {

if (target.hasownproperty(prop)) {

result[prop] = deepclone(target[prop])

}

}

return result;

}

// 无法复制函数

var o1 = json.parse(json.stringify(obj1));

5、reverse底层原理和扩展

// 改变原数组

array.prototype.myreverse = function () {

var len = this.length;

for (var i = 0; i < len; i++) {

var temp = this[i];

this[i] = this[len – 1 – i];

this[len – 1 – i] = temp;

}

return this;

}

6、圣杯模式的继承

function inherit(target, origin) {

function f() {};

f.prototype = origin.prototype;

target.prototype = new f();

target.prototype.constructor = target;

// 最终的原型指向

target.prop.uber = origin.prototype;

}

7、找出字符串中第一次只出现一次的字母

string.prototype.firstappear = function () {

var obj = {},

len = this.length;

for (var i = 0; i < len; i++) {

if (obj[this[i]]) {

obj[this[i]]++;

} else {

obj[this[i]] = 1;

}

}

for (var prop in obj) {

if (obj[prop] == 1) {

return prop;

}

}

}

8、找元素的第n级父元素

function parents(ele, n) {

while (ele && n) {

ele = ele.parentelement ? ele.parentelement : ele.parentnode;

n–;

}

return ele;

}

9、 返回元素的第n个兄弟节点

function retsibling(e, n) {

while (e && n) {

if (n > 0) {

if (e.nextelementsibling) {

e = e.nextelementsibling;

} else {

for (e = e.nextsibling; e && e.nodetype !== 1; e = e.nextsibling);

}

n–;

} else {

if (e.previouselementsibling) {

e = e.previouselementsibling;

} else {

for (e = e.previouselementsibling; e && e.nodetype !== 1; e = e.previouselementsibling);

}

n++;

}

}

return e;

}

10、封装mychildren,解决浏览器的兼容问题

function mychildren(e) {

var children = e.childnodes,

arr = [],

len = children.length;

for (var i = 0; i < len; i++) {

if (children[i].nodetype === 1) {

arr.push(children[i])

}

}

return arr;

}

11、判断元素有没有子元素

function haschildren(e) {

var children = e.childnodes,

len = children.length;

for (var i = 0; i < len; i++) {

if (children[i].nodetype === 1) {

return true;

}

}

return false;

}

12、我一个元素插入到另一个元素的后面

element.prototype.insertafter = function (target, elen) {

var nextelen = elen.nextelenmentsibling;

if (nextelen == null) {

this.appendchild(target);

} else {

this.insertbefore(target, nextelen);

}

}

13、返回当前的时间(年月日时分秒)

function getdatetime() {

var date = new date(),

year = date.getfullyear(),

month = date.getmonth() + 1,

day = date.getdate(),

hour = date.gethours() + 1,

minute = date.getminutes(),

second = date.getseconds();

month = checktime(month);

day = checktime(day);

hour = checktime(hour);

minute = checktime(minute);

second = checktime(second);

function checktime(i) {

if (i < 10) {

i = “0” + i;

}

return i;

}

return “” + year + “年” + month + “月” + day + “日” + hour + “时” + minute + “分” + second + “秒”

}

14、获得滚动条的滚动距离

function getscrolloffset() {

if (window.pagexoffset) {

return {

x: window.pagexoffset,

y: window.pageyoffset

}

} else {

return {

x: document.body.scrollleft + document.documentelement.scrollleft,

y: document.body.scrolltop + document.documentelement.scrolltop

}

}

}

15、获得视口的尺寸

function getviewportoffset() {

if (window.innerwidth) {

return {

w: window.innerwidth,

h: window.innerheight

}

} else {

// ie8及其以下

if (document.compatmode === “backcompat”) {

// 怪异模式

return {

w: document.body.clientwidth,

h: document.body.clientheight

}

} else {

// 标准模式

return {

w: document.documentelement.clientwidth,

h: document.documentelement.clientheight

}

}

}

}

16、获取任意元素的任意属性

function getstyle(elem, prop) {

return window.getcomputedstyle ? window.getcomputedstyle(elem, null)[prop] : elem.currentstyle[prop]

}

17、绑定事件的兼容代码

function addevent(elem, type, handle) {

if (elem.addeventlistener) { //非ie和非ie9

elem.addeventlistener(type, handle, false);

} else if (elem.attachevent) { //ie6到ie8

elem.attachevent(‘on’ + type, function () {

handle.call(elem);

})

} else {

elem[‘on’ + type] = handle;

}

}

18、解绑事件

function removeevent(elem, type, handle) {

if (elem.removeeventlistener) { //非ie和非ie9

elem.removeeventlistener(type, handle, false);

} else if (elem.detachevent) { //ie6到ie8

elem.detachevent(‘on’ + type, handle);

} else {

elem[‘on’ + type] = null;

}

}

19、取消冒泡的兼容代码

function stopbubble(e) {

if (e && e.stoppropagation) {

e.stoppropagation();

} else {

window.event.cancelbubble = true;

}

}

20、检验字符串是否是回文

function ispalina(str) {

if (object.prototype.tostring.call(str) !== ‘[object string]’) {

return false;

}

var len = str.length;

for (var i = 0; i < len / 2; i++) {

if (str[i] != str[len – 1 – i]) {

return false;

}

}

return true;

}

21、检验字符串是否是回文

function ispalindrome(str) {

str = str.replace(/w/g, ”).tolowercase();

console.log(str)

return (str == str.split(”).reverse().join(”))

}

22、兼容getelementsbyclassname方法

element.prototype.getelementsbyclassname = document.prototype.getelementsbyclassname = function (_classname) {

var alldomarray = document.getelementsbytagname(‘*’);

var lastdomarray = [];

function trimspace(strclass) {

var reg = /s+/g;

return strclass.replace(reg, ‘ ‘).trim()

}

for (var i = 0; i < alldomarray.length; i++) {

var classarray = trimspace(alldomarray[i].classname).split(‘ ‘);

for (var j = 0; j < classarray.length; j++) {

if (classarray[j] == _classname) {

lastdomarray.push(alldomarray[i]);

break;

}

}

}

return lastdomarray;

}

23、运动函数

function animate(obj, json, callback) {

clearinterval(obj.timer);

var speed,

current;

obj.timer = setinterval(function () {

var lock = true;

for (var prop in json) {

if (prop == ‘opacity’) {

current = parsefloat(window.getcomputedstyle(obj, null)[prop]) * 100;

} else {

current = parseint(window.getcomputedstyle(obj, null)[prop]);

}

speed = (json[prop] – current) / 7;

speed = speed > 0 ? math.ceil(speed) : math.floor(speed);

if (prop == ‘opacity’) {

obj.style[prop] = (current + speed) / 100;

} else {

obj.style[prop] = current + speed + ‘px’;

}

if (current != json[prop]) {

lock = false;

}

}

if (lock) {

clearinterval(obj.timer);

typeof callback == ‘function’ ? callback() : ”;

}

}, 30)

}

js回调函数原理(教你判断下跌还是回调)

24、弹性运动

function elasticmovement(obj, target) {

clearinterval(obj.timer);

var ispeed = 40,

a, u = 0.8;

obj.timer = setinterval(function () {

a = (target – obj.offsetleft) / 8;

ispeed = ispeed + a;

ispeed = ispeed * u;

if (math.abs(ispeed) <= 1 && math.abs(a) <= 1) {

console.log(‘over’)

clearinterval(obj.timer);

obj.style.left = target + ‘px’;

} else {

obj.style.left = obj.offsetleft + ispeed + ‘px’;

}

}, 30);

}

25、封装自己的foreach方法

array.prototype.myforeach = function (func, obj) {

var len = this.length;

var _this = arguments[1] ? arguments[1] : window;

// var _this=arguments[1]||window;

for (var i = 0; i < len; i++) {

func.call(_this, this[i], i, this)

}

}

26、封装自己的filter方法

array.prototype.myfilter = function (func, obj) {

var len = this.length;

var arr = [];

var _this = arguments[1] || window;

for (var i = 0; i < len; i++) {

func.call(_this, this[i], i, this) && arr.push(this[i]);

}

return arr;

}

27、数组map方法

array.prototype.mymap = function (func) {

var arr = [];

var len = this.length;

var _this = arguments[1] || window;

for (var i = 0; i < len; i++) {

arr.push(func.call(_this, this[i], i, this));

}

return arr;

}

28、数组every方法

array.prototype.myevery = function (func) {

var flag = true;

var len = this.length;

var _this = arguments[1] || window;

for (var i = 0; i < len; i++) {

if (func.apply(_this, [this[i], i, this]) == false) {

flag = false;

break;

}

}

return flag;

}

29、数组reduce方法

array.prototype.myreduce = function (func, initialvalue) {

var len = this.length,

nextvalue,

i;

if (!initialvalue) {

// 没有传第二个参数

nextvalue = this[0];

i = 1;

} else {

// 传了第二个参数

nextvalue = initialvalue;

i = 0;

}

for (; i < len; i++) {

nextvalue = func(nextvalue, this[i], i, this);

}

return nextvalue;

}

30、获取url中的参数

function getwindonhref() {

var shref = window.location.href;

var args = shref.split(‘?’);

if (args[0] === shref) {

return ”;

}

var hrefarr = args[1].split(‘#’)[0].split(‘&’);

var obj = {};

for (var i = 0; i < hrefarr.length; i++) {

hrefarr[i] = hrefarr[i].split(‘=’);

obj[hrefarr[i][0]] = hrefarr[i][1];

}

return obj;

}

31、数组排序

// 快排 [left] + min + [right]

function quickarr(arr) {

if (arr.length <= 1) {

return arr;

}

var left = [],

right = [];

var pindex = math.floor(arr.length / 2);

var p = arr.splice(pindex, 1)[0];

for (var i = 0; i < arr.length; i++) {

if (arr[i] <= p) {

left.push(arr[i]);

} else {

right.push(arr[i]);

}

}

// 递归

return quickarr(left).concat([p], quickarr(right));

}

// 冒泡

function bubblesort(arr) {

for (var i = 0; i < arr.length – 1; i++) {

for (var j = i + 1; j < arr.length; j++) {

if (arr[i] > arr[j]) {

var temp = arr[i];

arr[i] = arr[j];

arr[j] = temp;

}

}

}

return arr;

}

function bubblesort(arr) {

var len = arr.length;

for (var i = 0; i < len – 1; i++) {

for (var j = 0; j < len – 1 – i; j++) {

if (arr[j] > arr[j + 1]) {

var temp = arr[j];

arr[j] = arr[j + 1];

arr[j + 1] = temp;

}

}

}

return arr;

}

32、遍历dom树

// 给定页面上的dom元素,将访问元素本身及其所有后代(不仅仅是它的直接子元素)

// 对于每个访问的元素,函数将元素传递给提供的回调函数

function traverse(element, callback) {

callback(element);

var list = element.children;

for (var i = 0; i < list.length; i++) {

traverse(list[i], callback);

}

}

33、原生js封装ajax

function ajax(method, url, callback, data, flag) {

var xhr;

flag = flag || true;

method = method.touppercase();

if (window.xmlhttprequest) {

xhr = new xmlhttprequest();

} else {

xhr = new activexobject(‘microsoft.xmlhttp’);

}

xhr.onreadystatechange = function () {

if (xhr.readystate == 4 && xhr.status == 200) {

console.log(2)

callback(xhr.responsetext);

}

}

if (method == ‘get’) {

var date = new date(),

timer = date.gettime();

xhr.open(‘get’, url + ‘?’ + data + ‘&timer’ + timer, flag);

xhr.send()

} else if (method == ‘post’) {

xhr.open(‘post’, url, flag);

xhr.setrequestheader(‘content-type’, ‘application/x-www-form-urlencoded’);

xhr.send(data);

}

}

34、异步加载script

function loadscript(url, callback) {

var oscript = document.createelement(‘script’);

if (oscript.readystate) { // ie8及以下版本

oscript.onreadystatechange = function () {

if (oscript.readystate === ‘complete’ || oscript.readystate === ‘loaded’) {

callback();

}

}

} else {

oscript.onload = function () {

callback()

};

}

oscript.src = url;

document.body.appendchild(oscript);

}

35、cookie管理

var cookie = {

set: function (name, value, time) {

document.cookie = name + ‘=’ + value + ‘; max-age=’ + time;

return this;

},

remove: function (name) {

return this.setcookie(name, ”, -1);

},

get: function (name, callback) {

var allcookiearr = document.cookie.split(‘; ‘);

for (var i = 0; i < allcookiearr.length; i++) {

var itemcookiearr = allcookiearr[i].split(‘=’);

if (itemcookiearr[0] === name) {

return itemcookiearr[1]

}

}

return undefined;

}

}

36、实现bind()方法

function.prototype.mybind = function (target) {

var target = target || window;

var _args1 = [].slice.call(arguments, 1);

var self = this;

var temp = function () {};

var f = function () {

var _args2 = [].slice.call(arguments, 0);

var parasarr = _args1.concat(_args2);

return self.apply(this instanceof temp ? this : target, parasarr)

}

temp.prototype = self.prototype;

f.prototype = new temp();

return f;

}

37、实现call()方法

function.prototype.mycall = function () {

var ctx = arguments[0] || window;

ctx.fn = this;

var args = [];

for (var i = 1; i < arguments.length; i++) {

args.push(arguments[i])

}

var result = ctx.fn(…args);

delete ctx.fn;

return result;

}

js回调函数原理(教你判断下跌还是回调)

38、实现apply()方法

function.prototype.myapply = function () {

var ctx = arguments[0] || window;

ctx.fn = this;

if (!arguments[1]) {

var result = ctx.fn();

delete ctx.fn;

return result;

}

var result = ctx.fn(…arguments[1]);

delete ctx.fn;

return result;

}

39、防抖

function debounce(handle, delay) {

var timer = null;

return function () {

var _self = this,

_args = arguments;

cleartimeout(timer);

timer = settimeout(function () {

handle.apply(_self, _args)

}, delay)

}

}

40、节流

function throttle(handler, wait) {

var lasttime = 0;

return function (e) {

var nowtime = new date().gettime();

if (nowtime – lasttime > wait) {

handler.apply(this, arguments);

lasttime = nowtime;

}

}

}

41、requestanimframe兼容性方法

window.requestanimframe = (function () {

return window.requestanimationframe ||

window.webkitrequestanimationframe ||

window.mozrequestanimationframe ||

function (callback) {

window.settimeout(callback, 1000 / 60);

};

})();

42、cancelanimframe兼容性方法

window.cancelanimframe = (function () {

return window.cancelanimationframe ||

window.webkitcancelanimationframe ||

window.mozcancelanimationframe ||

function (id) {

window.cleartimeout(id);

};

})();

43、jsonp底层方法

function jsonp(url, callback) {

var oscript = document.createelement(‘script’);

if (oscript.readystate) { // ie8及以下版本

oscript.onreadystatechange = function () {

if (oscript.readystate === ‘complete’ || oscript.readystate === ‘loaded’) {

callback();

}

}

} else {

oscript.onload = function () {

callback()

};

}

oscript.src = url;

document.body.appendchild(oscript);

}

44、获取url上的参数

function geturlparam(surl, skey) {

var result = {};

surl.replace(/(w+)=(w+)(?=[&|#])/g, function (ele, key, val) {

if (!result[key]) {

result[key] = val;

} else {

var temp = result[key];

result[key] = [].concat(temp, val);

}

})

if (!skey) {

return result;

} else {

return result[skey] || ”;

}

}

45、格式化时间

function formatdate(t, str) {

var obj = {

yyyy: t.getfullyear(),

yy: (“” + t.getfullyear()).slice(-2),

m: t.getmonth() + 1,

mm: (“0” + (t.getmonth() + 1)).slice(-2),

d: t.getdate(),

dd: (“0” + t.getdate()).slice(-2),

h: t.gethours(),

hh: (“0” + t.gethours()).slice(-2),

h: t.gethours() % 12,

hh: (“0” + t.gethours() % 12).slice(-2),

m: t.getminutes(),

mm: (“0” + t.getminutes()).slice(-2),

s: t.getseconds(),

ss: (“0” + t.getseconds()).slice(-2),

w: [‘日’, ‘一’, ‘二’, ‘三’, ‘四’, ‘五’, ‘六’][t.getday()]

};

return str.replace(/([a-z]+)/ig, function ($1) {

return obj[$1]

});

}

46、验证邮箱的正则表达式

function isavailableemail(semail) {

var reg = /^([w+.])+@w+([.]w+)+$/

return reg.test(semail)

}

47、函数颗粒化

//是把接受多个参数的函数变换成接受一个单一参数(最初函数的第一个参数)的函数,并且返回接受余下的参数且返回结果的新函数的技术

function curryit(fn) {

var length = fn.length,

args = [];

var result = function (arg) {

args.push(arg);

length–;

if (length <= 0) {

return fn.apply(this, args);

} else {

return result;

}

}

return result;

}

48、大数相加

function sumbignumber(a, b) {

var res = ”, //结果

temp = 0; //按位加的结果及进位

a = a.split(”);

b = b.split(”);

while (a.length || b.length || temp) {

//~~按位非 1.类型转换,转换成数字 2.~~undefined==0

temp += ~~a.pop() + ~~b.pop();

res = (temp % 10) + res;

temp = temp > 9;

}

return res.replace(/^0+/, ”);

}

1、输入一个值,返回其数据类型**

function type(para) {

return object.prototype.tostring.call(para)

}

2、数组去重

function unique1(arr) {

return […new set(arr)]

}

function unique2(arr) {

var obj = {};

return arr.filter(ele => {

if (!obj[ele]) {

obj[ele] = true;

return true;

}

})

}

function unique3(arr) {

var result = [];

arr.foreach(ele => {

if (result.indexof(ele) == -1) {

result.push(ele)

}

})

return result;

}

3、字符串去重

string.prototype.unique = function () {

var obj = {},

str = ”,

len = this.length;

for (var i = 0; i < len; i++) {

if (!obj[this[i]]) {

str += this[i];

obj[this[i]] = true;

}

}

return str;

}

###### //去除连续的字符串

function uniq(str) {

return str.replace(/(w)1+/g, ‘$1’)

}

js回调函数原理(教你判断下跌还是回调)

4、深拷贝 浅拷贝

//深克隆(深克隆不考虑函数)

function deepclone(obj, result) {

var result = result || {};

for (var prop in obj) {

if (obj.hasownproperty(prop)) {

if (typeof obj[prop] == ‘object’ && obj[prop] !== null) {

// 引用值(obj/array)且不为null

if (object.prototype.tostring.call(obj[prop]) == ‘[object object]’) {

// 对象

result[prop] = {};

} else {

// 数组

result[prop] = [];

}

deepclone(obj[prop], result[prop])

} else {

// 原始值或func

result[prop] = obj[prop]

}

}

}

return result;

}

// 深浅克隆是针对引用值

function deepclone(target) {

if (typeof (target) !== ‘object’) {

return target;

}

var result;

if (object.prototype.tostring.call(target) == ‘[object array]’) {

// 数组

result = []

} else {

// 对象

result = {};

}

for (var prop in target) {

if (target.hasownproperty(prop)) {

result[prop] = deepclone(target[prop])

}

}

return result;

}

// 无法复制函数

var o1 = json.parse(json.stringify(obj1));

5、reverse底层原理和扩展

// 改变原数组

array.prototype.myreverse = function () {

var len = this.length;

for (var i = 0; i < len; i++) {

var temp = this[i];

this[i] = this[len – 1 – i];

this[len – 1 – i] = temp;

}

return this;

}

6、圣杯模式的继承

function inherit(target, origin) {

function f() {};

f.prototype = origin.prototype;

target.prototype = new f();

target.prototype.constructor = target;

// 最终的原型指向

target.prop.uber = origin.prototype;

}

7、找出字符串中第一次只出现一次的字母

string.prototype.firstappear = function () {

var obj = {},

len = this.length;

for (var i = 0; i < len; i++) {

if (obj[this[i]]) {

obj[this[i]]++;

} else {

obj[this[i]] = 1;

}

}

for (var prop in obj) {

if (obj[prop] == 1) {

return prop;

}

}

}

8、找元素的第n级父元素

function parents(ele, n) {

while (ele && n) {

ele = ele.parentelement ? ele.parentelement : ele.parentnode;

n–;

}

return ele;

}

9、 返回元素的第n个兄弟节点

function retsibling(e, n) {

while (e && n) {

if (n > 0) {

if (e.nextelementsibling) {

e = e.nextelementsibling;

} else {

for (e = e.nextsibling; e && e.nodetype !== 1; e = e.nextsibling);

}

n–;

} else {

if (e.previouselementsibling) {

e = e.previouselementsibling;

} else {

for (e = e.previouselementsibling; e && e.nodetype !== 1; e = e.previouselementsibling);

}

n++;

}

}

return e;

}

10、封装mychildren,解决浏览器的兼容问题

function mychildren(e) {

var children = e.childnodes,

arr = [],

len = children.length;

for (var i = 0; i < len; i++) {

if (children[i].nodetype === 1) {

arr.push(children[i])

}

}

return arr;

}

11、判断元素有没有子元素

function haschildren(e) {

var children = e.childnodes,

len = children.length;

for (var i = 0; i < len; i++) {

if (children[i].nodetype === 1) {

return true;

}

}

return false;

}

12、我一个元素插入到另一个元素的后面

element.prototype.insertafter = function (target, elen) {

var nextelen = elen.nextelenmentsibling;

if (nextelen == null) {

this.appendchild(target);

} else {

this.insertbefore(target, nextelen);

}

}

13、返回当前的时间(年月日时分秒)

function getdatetime() {

var date = new date(),

year = date.getfullyear(),

month = date.getmonth() + 1,

day = date.getdate(),

hour = date.gethours() + 1,

minute = date.getminutes(),

second = date.getseconds();

month = checktime(month);

day = checktime(day);

hour = checktime(hour);

minute = checktime(minute);

second = checktime(second);

function checktime(i) {

if (i < 10) {

i = “0” + i;

}

return i;

}

return “” + year + “年” + month + “月” + day + “日” + hour + “时” + minute + “分” + second + “秒”

}

14、获得滚动条的滚动距离

function getscrolloffset() {

if (window.pagexoffset) {

return {

x: window.pagexoffset,

y: window.pageyoffset

}

} else {

return {

x: document.body.scrollleft + document.documentelement.scrollleft,

y: document.body.scrolltop + document.documentelement.scrolltop

}

}

}

15、获得视口的尺寸

function getviewportoffset() {

if (window.innerwidth) {

return {

w: window.innerwidth,

h: window.innerheight

}

} else {

// ie8及其以下

if (document.compatmode === “backcompat”) {

// 怪异模式

return {

w: document.body.clientwidth,

h: document.body.clientheight

}

} else {

// 标准模式

return {

w: document.documentelement.clientwidth,

h: document.documentelement.clientheight

}

}

}

}

16、获取任意元素的任意属性

function getstyle(elem, prop) {

return window.getcomputedstyle ? window.getcomputedstyle(elem, null)[prop] : elem.currentstyle[prop]

}

17、绑定事件的兼容代码

function addevent(elem, type, handle) {

if (elem.addeventlistener) { //非ie和非ie9

elem.addeventlistener(type, handle, false);

} else if (elem.attachevent) { //ie6到ie8

elem.attachevent(‘on’ + type, function () {

handle.call(elem);

})

} else {

elem[‘on’ + type] = handle;

}

}

18、解绑事件

function removeevent(elem, type, handle) {

if (elem.removeeventlistener) { //非ie和非ie9

elem.removeeventlistener(type, handle, false);

} else if (elem.detachevent) { //ie6到ie8

elem.detachevent(‘on’ + type, handle);

} else {

elem[‘on’ + type] = null;

}

}

19、取消冒泡的兼容代码

function stopbubble(e) {

if (e && e.stoppropagation) {

e.stoppropagation();

} else {

window.event.cancelbubble = true;

}

}

20、检验字符串是否是回文

function ispalina(str) {

if (object.prototype.tostring.call(str) !== ‘[object string]’) {

return false;

}

var len = str.length;

for (var i = 0; i < len / 2; i++) {

if (str[i] != str[len – 1 – i]) {

return false;

}

}

return true;

}

21、检验字符串是否是回文

function ispalindrome(str) {

str = str.replace(/w/g, ”).tolowercase();

console.log(str)

return (str == str.split(”).reverse().join(”))

}

22、兼容getelementsbyclassname方法

element.prototype.getelementsbyclassname = document.prototype.getelementsbyclassname = function (_classname) {

var alldomarray = document.getelementsbytagname(‘*’);

var lastdomarray = [];

function trimspace(strclass) {

var reg = /s+/g;

return strclass.replace(reg, ‘ ‘).trim()

}

for (var i = 0; i < alldomarray.length; i++) {

var classarray = trimspace(alldomarray[i].classname).split(‘ ‘);

for (var j = 0; j < classarray.length; j++) {

if (classarray[j] == _classname) {

lastdomarray.push(alldomarray[i]);

break;

}

}

}

return lastdomarray;

}

23、运动函数

function animate(obj, json, callback) {

clearinterval(obj.timer);

var speed,

current;

obj.timer = setinterval(function () {

var lock = true;

for (var prop in json) {

if (prop == ‘opacity’) {

current = parsefloat(window.getcomputedstyle(obj, null)[prop]) * 100;

} else {

current = parseint(window.getcomputedstyle(obj, null)[prop]);

}

speed = (json[prop] – current) / 7;

speed = speed > 0 ? math.ceil(speed) : math.floor(speed);

if (prop == ‘opacity’) {

obj.style[prop] = (current + speed) / 100;

} else {

obj.style[prop] = current + speed + ‘px’;

}

if (current != json[prop]) {

lock = false;

}

}

if (lock) {

clearinterval(obj.timer);

typeof callback == ‘function’ ? callback() : ”;

}

}, 30)

}

js回调函数原理(教你判断下跌还是回调)

24、弹性运动

function elasticmovement(obj, target) {

clearinterval(obj.timer);

var ispeed = 40,

a, u = 0.8;

obj.timer = setinterval(function () {

a = (target – obj.offsetleft) / 8;

ispeed = ispeed + a;

ispeed = ispeed * u;

if (math.abs(ispeed) <= 1 && math.abs(a) <= 1) {

console.log(‘over’)

clearinterval(obj.timer);

obj.style.left = target + ‘px’;

} else {

obj.style.left = obj.offsetleft + ispeed + ‘px’;

}

}, 30);

}

25、封装自己的foreach方法

array.prototype.myforeach = function (func, obj) {

var len = this.length;

var _this = arguments[1] ? arguments[1] : window;

// var _this=arguments[1]||window;

for (var i = 0; i < len; i++) {

func.call(_this, this[i], i, this)

}

}

26、封装自己的filter方法

array.prototype.myfilter = function (func, obj) {

var len = this.length;

var arr = [];

var _this = arguments[1] || window;

for (var i = 0; i < len; i++) {

func.call(_this, this[i], i, this) && arr.push(this[i]);

}

return arr;

}

27、数组map方法

array.prototype.mymap = function (func) {

var arr = [];

var len = this.length;

var _this = arguments[1] || window;

for (var i = 0; i < len; i++) {

arr.push(func.call(_this, this[i], i, this));

}

return arr;

}

28、数组every方法

array.prototype.myevery = function (func) {

var flag = true;

var len = this.length;

var _this = arguments[1] || window;

for (var i = 0; i < len; i++) {

if (func.apply(_this, [this[i], i, this]) == false) {

flag = false;

break;

}

}

return flag;

}

29、数组reduce方法

array.prototype.myreduce = function (func, initialvalue) {

var len = this.length,

nextvalue,

i;

if (!initialvalue) {

// 没有传第二个参数

nextvalue = this[0];

i = 1;

} else {

// 传了第二个参数

nextvalue = initialvalue;

i = 0;

}

for (; i < len; i++) {

nextvalue = func(nextvalue, this[i], i, this);

}

return nextvalue;

}

30、获取url中的参数

function getwindonhref() {

var shref = window.location.href;

var args = shref.split(‘?’);

if (args[0] === shref) {

return ”;

}

var hrefarr = args[1].split(‘#’)[0].split(‘&’);

var obj = {};

for (var i = 0; i < hrefarr.length; i++) {

hrefarr[i] = hrefarr[i].split(‘=’);

obj[hrefarr[i][0]] = hrefarr[i][1];

}

return obj;

}

31、数组排序

// 快排 [left] + min + [right]

function quickarr(arr) {

if (arr.length <= 1) {

return arr;

}

var left = [],

right = [];

var pindex = math.floor(arr.length / 2);

var p = arr.splice(pindex, 1)[0];

for (var i = 0; i < arr.length; i++) {

if (arr[i] <= p) {

left.push(arr[i]);

} else {

right.push(arr[i]);

}

}

// 递归

return quickarr(left).concat([p], quickarr(right));

}

// 冒泡

function bubblesort(arr) {

for (var i = 0; i < arr.length – 1; i++) {

for (var j = i + 1; j < arr.length; j++) {

if (arr[i] > arr[j]) {

var temp = arr[i];

arr[i] = arr[j];

arr[j] = temp;

}

}

}

return arr;

}

function bubblesort(arr) {

var len = arr.length;

for (var i = 0; i < len – 1; i++) {

for (var j = 0; j < len – 1 – i; j++) {

if (arr[j] > arr[j + 1]) {

var temp = arr[j];

arr[j] = arr[j + 1];

arr[j + 1] = temp;

}

}

}

return arr;

}

32、遍历dom树

// 给定页面上的dom元素,将访问元素本身及其所有后代(不仅仅是它的直接子元素)

// 对于每个访问的元素,函数将元素传递给提供的回调函数

function traverse(element, callback) {

callback(element);

var list = element.children;

for (var i = 0; i < list.length; i++) {

traverse(list[i], callback);

}

}

33、原生js封装ajax

function ajax(method, url, callback, data, flag) {

var xhr;

flag = flag || true;

method = method.touppercase();

if (window.xmlhttprequest) {

xhr = new xmlhttprequest();

} else {

xhr = new activexobject(‘microsoft.xmlhttp’);

}

xhr.onreadystatechange = function () {

if (xhr.readystate == 4 && xhr.status == 200) {

console.log(2)

callback(xhr.responsetext);

}

}

if (method == ‘get’) {

var date = new date(),

timer = date.gettime();

xhr.open(‘get’, url + ‘?’ + data + ‘&timer’ + timer, flag);

xhr.send()

} else if (method == ‘post’) {

xhr.open(‘post’, url, flag);

xhr.setrequestheader(‘content-type’, ‘application/x-www-form-urlencoded’);

xhr.send(data);

}

}

34、异步加载script

function loadscript(url, callback) {

var oscript = document.createelement(‘script’);

if (oscript.readystate) { // ie8及以下版本

oscript.onreadystatechange = function () {

if (oscript.readystate === ‘complete’ || oscript.readystate === ‘loaded’) {

callback();

}

}

} else {

oscript.onload = function () {

callback()

};

}

oscript.src = url;

document.body.appendchild(oscript);

}

35、cookie管理

var cookie = {

set: function (name, value, time) {

document.cookie = name + ‘=’ + value + ‘; max-age=’ + time;

return this;

},

remove: function (name) {

return this.setcookie(name, ”, -1);

},

get: function (name, callback) {

var allcookiearr = document.cookie.split(‘; ‘);

for (var i = 0; i < allcookiearr.length; i++) {

var itemcookiearr = allcookiearr[i].split(‘=’);

if (itemcookiearr[0] === name) {

return itemcookiearr[1]

}

}

return undefined;

}

}

36、实现bind()方法

function.prototype.mybind = function (target) {

var target = target || window;

var _args1 = [].slice.call(arguments, 1);

var self = this;

var temp = function () {};

var f = function () {

var _args2 = [].slice.call(arguments, 0);

var parasarr = _args1.concat(_args2);

return self.apply(this instanceof temp ? this : target, parasarr)

}

temp.prototype = self.prototype;

f.prototype = new temp();

return f;

}

37、实现call()方法

function.prototype.mycall = function () {

var ctx = arguments[0] || window;

ctx.fn = this;

var args = [];

for (var i = 1; i < arguments.length; i++) {

args.push(arguments[i])

}

var result = ctx.fn(…args);

delete ctx.fn;

return result;

}

js回调函数原理(教你判断下跌还是回调)

38、实现apply()方法

function.prototype.myapply = function () {

var ctx = arguments[0] || window;

ctx.fn = this;

if (!arguments[1]) {

var result = ctx.fn();

delete ctx.fn;

return result;

}

var result = ctx.fn(…arguments[1]);

delete ctx.fn;

return result;

}

39、防抖

function debounce(handle, delay) {

var timer = null;

return function () {

var _self = this,

_args = arguments;

cleartimeout(timer);

timer = settimeout(function () {

handle.apply(_self, _args)

}, delay)

}

}

40、节流

function throttle(handler, wait) {

var lasttime = 0;

return function (e) {

var nowtime = new date().gettime();

if (nowtime – lasttime > wait) {

handler.apply(this, arguments);

lasttime = nowtime;

}

}

}

41、requestanimframe兼容性方法

window.requestanimframe = (function () {

return window.requestanimationframe ||

window.webkitrequestanimationframe ||

window.mozrequestanimationframe ||

function (callback) {

window.settimeout(callback, 1000 / 60);

};

})();

42、cancelanimframe兼容性方法

window.cancelanimframe = (function () {

return window.cancelanimationframe ||

window.webkitcancelanimationframe ||

window.mozcancelanimationframe ||

function (id) {

window.cleartimeout(id);

};

})();

43、jsonp底层方法

function jsonp(url, callback) {

var oscript = document.createelement(‘script’);

if (oscript.readystate) { // ie8及以下版本

oscript.onreadystatechange = function () {

if (oscript.readystate === ‘complete’ || oscript.readystate === ‘loaded’) {

callback();

}

}

} else {

oscript.onload = function () {

callback()

};

}

oscript.src = url;

document.body.appendchild(oscript);

}

44、获取url上的参数

function geturlparam(surl, skey) {

var result = {};

surl.replace(/(w+)=(w+)(?=[&|#])/g, function (ele, key, val) {

if (!result[key]) {

result[key] = val;

} else {

var temp = result[key];

result[key] = [].concat(temp, val);

}

})

if (!skey) {

return result;

} else {

return result[skey] || ”;

}

}

45、格式化时间

function formatdate(t, str) {

var obj = {

yyyy: t.getfullyear(),

yy: (“” + t.getfullyear()).slice(-2),

m: t.getmonth() + 1,

mm: (“0” + (t.getmonth() + 1)).slice(-2),

d: t.getdate(),

dd: (“0” + t.getdate()).slice(-2),

h: t.gethours(),

hh: (“0” + t.gethours()).slice(-2),

h: t.gethours() % 12,

hh: (“0” + t.gethours() % 12).slice(-2),

m: t.getminutes(),

mm: (“0” + t.getminutes()).slice(-2),

s: t.getseconds(),

ss: (“0” + t.getseconds()).slice(-2),

w: [‘日’, ‘一’, ‘二’, ‘三’, ‘四’, ‘五’, ‘六’][t.getday()]

};

return str.replace(/([a-z]+)/ig, function ($1) {

return obj[$1]

});

}

46、验证邮箱的正则表达式

function isavailableemail(semail) {

var reg = /^([w+.])+@w+([.]w+)+$/

return reg.test(semail)

}

47、函数颗粒化

//是把接受多个参数的函数变换成接受一个单一参数(最初函数的第一个参数)的函数,并且返回接受余下的参数且返回结果的新函数的技术

function curryit(fn) {

var length = fn.length,

args = [];

var result = function (arg) {

args.push(arg);

length–;

if (length <= 0) {

return fn.apply(this, args);

} else {

return result;

}

}

return result;

}

48、大数相加

function sumbignumber(a, b) {

var res = ”, //结果

temp = 0; //按位加的结果及进位

a = a.split(”);

b = b.split(”);

while (a.length || b.length || temp) {

//~~按位非 1.类型转换,转换成数字 2.~~undefined==0

temp += ~~a.pop() + ~~b.pop();

res = (temp % 10) + res;

temp = temp > 9;

}

return res.replace(/^0+/, ”);

}

49、单例模式

function getsingle(func) {

var result;

return function () {

if (!result) {

result = new func(arguments);

}

return result;

}

}

49、单例模式

function getsingle(func) {

var result;

return function () {

if (!result) {

result = new func(arguments);

}

return result;

}

}