javascript基础学习自我总结

1.JavaScript循环

for (var i=0; i<=10;i++){
    if (i==3){
        continue;//当i=3时终端循环,继续下面
    }
    document.write("数字是 " + i)
    document.write("<br />")
}

var x;
var mycars = new Array()
mycars[0] = "宝马"
mycars[1] = "奔驰"
mycars[2] = "宾利"

for (x in mycars){
    document.write(mycars[x] + "<br />")
}

2.try ... catch语句

var txt="";
function message(){
try
   {
   adddlert("Welcome guest!"); //不存在此方法,会报异常
   }
catch(err) {
   txt="本页中存在错误。\n\n";
   txt+="错误描述：" + err.description + "\n\n";
   txt+="点击“确定”继续。\n\n";
   console.log(txt);
   }
}

3.throws语句

var x=prompt("请输入 0 至 10 之间的数：","")
try{ 
    if(x>10)   throw "Err1" ;
    else if(x<0) throw "Err2";
    else if(isNaN(x)) throw "Err3";
} catch(er){
    if(er=="Err1") alert("错误！该值太大！");
    if(er == "Err2")  alert("错误！该值太小！") ;
    if(er == "Err3")   alert("错误！该值不是数字！") ;
}

4.onerror事件

onerror=handleErr;  
var txt="";

function handleErr(msg,url,l){
    txt="本页中存在错误。\n\n";
    txt+="错误：" + msg + "\n";
    txt+="URL: " + url + "\n";
    txt+="行：" + l + "\n\n";
    txt+="点击“确定”继续。\n\n";
    alert(txt)
    return true
}

function message(){
    adddlert("Welcome guest!") //没有此方法,就会触发 onerror事件
}

5.获取浏览器版本

var browser=navigator.appName;
var b_version=navigator.appVersion;
var version=parseFloat(b_version);
document.write("浏览器名称："+ browser);
document.write("<br />");
document.write("浏览器版本："+ version);

6.创建一个cookie

function getCookie(c_name) {
	if(document.cookie.length > 0) {
		c_start = document.cookie.indexOf(c_name + "=")
		if(c_start != -1) {
			c_start = c_start + c_name.length + 1
			c_end = document.cookie.indexOf(";", c_start)
			if(c_end == -1) c_end = document.cookie.length
			return unescape(document.cookie.substring(c_start, c_end))
		}
	}
	return ""
}

function setCookie(c_name, value, expiredays) {
	var exdate = new Date()
	exdate.setDate(exdate.getDate() + expiredays)
	document.cookie = c_name + "=" + escape(value) +   //escape编码函数   unescape解码函数
		((expiredays == null) ? "" : "; expires=" + exdate.toGMTString())
}

function checkCookie() {
	username = getCookie('username')
	if(username != null && username != "") {
		alert('Welcome again ' + username + '!');
	} else {
		username = prompt('Please enter your name:', "")
		if(username != null && username != "") {
			setCookie('username', username, 365);
		}
	}
}

7.定时器函数

var c = 0
var t
//启用定时器函数
function timedCount() {
	document.getElementById('txt').value = c
	c = c + 1
	t = setTimeout("timedCount()", 1000)
}
//停止定时器函数
function stopCount() {
	c = 0;
	setTimeout("document.getElementById('txt').value=0", 0);
	clearTimeout(t);
}

function startTime() {  //使用定时器做时钟
	var today = new Date()
	var h = today.getHours()
	var m = today.getMinutes()
	var s = today.getSeconds()
	// add a zero in front of numbers<10
	m = checkTime(m)
	s = checkTime(s)
	document.getElementById('txt').innerHTML = h + ":" + m + ":" + s
	t = setTimeout('startTime()', 500)
}

function checkTime(i) {
	if(i < 10) {
		i = "0" + i
	}
	return i
}

8.创建对象示例

personObj=new Object()
personObj.firstname="John";
personObj.lastname="Adams";
personObj.age=35;
personObj.eyecolor="black";

document.write(personObj.firstname + " 的年龄是 " + personObj.age + " 岁。");

9.对象模板

function person(firstname, lastname, age, eyecolor) {
	this.firstname = firstname;
	this.lastname = lastname;
	this.age = age;
	this.eyecolor = eyecolor;
}

myFather = new person("John", "Adams", 35, "black");

document.write(myFather.firstname + " 的年龄是 " + myFather.age + " 岁。");

10.数组函数

var mycars = new Array()
mycars[0] = "Saab";
mycars[1] = "Volvo";
mycars[2] = "BMW";

for(i = 0; i < mycars.length; i++) {
	document.write(mycars[i] + "<br />");
}

11.获取url中的参数

/**
 * 截取路径上字符串的方法.1
 * @param {Object} name
 */
function getQueryString(name) {
	var reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)', 'i');
	var r = window.location.search.substr(1).match(reg);
	if(r != null) {
		return unescape(r[2]);
	}
	return null;
}
/**
 * split拆分法
 */
function getRequest() {
	var url = window.location.search;
	var theRequest = new Object();
	if(url.indexOf("?") != -1) {
		var str = url.substr(1);
		strs = str.split("&");
		for(var i = 0; i < strs.length; i++) {
			theRequest[strs[i].split("=")[0]] = unescape(strs[i].split("=")[1]);
		}
	}
	return theRequest;
}
/**
 * 方法三
 * @param {Object} name
 */
function GetQueryString(name) {
	var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
	var r = window.location.search.substr(1).match(reg); //获取url中"?"符后的字符串并正则匹配
	var context = "";
	if(r != null)
		context = r[2];
	reg = null;
	r = null;
	return context == null || context == "" || context == "undefined" ? "" : context;
}
/**
 * 截取路径上?后面的参数
 */
function getRequest() {
	var url = location.search;
	if(url.indexOf('?') != -1) {
		var str = url.substr(1);
		var strs = str.split("=");
		return strs[1];
	}

}