JavaScript常用字符串与数组扩展函数小结

string对象的扩展函数：

string.prototype.trim = function() { 
  return this.replace(/^\s+|\s+$/g,""); 
} 
string.prototype.ltrim = function() { 
  return this.replace(/^\s+/g,""); 
} 
string.prototype.rtrim = function() { 
  return this.replace(/\s+$/g,""); 
} 
string.prototype.splitandtrim = function($delimiter, $limit) 
{ 
  var $ss = this.split($delimiter, $limit); 
  for(var $i=0; $i<$ss.length; $i++) 
    $ss[$i] = $ss[$i].trim(); 
 
  return $ss; 
} 
string.prototype.htmlentities = function () { 
  return this.replace(/&/g,'&').replace(/</g,'<').replace(/>/g,'>'); 
} 
string.prototype.striptags = function () { 
  return this.replace(/<([^>]+)>/g,''); 
} 
string.prototype.toarray = function() { 
  return this.split(''); 
} 
string.prototype.tointarray = function() { 
  var returnarray = []; 
  for (var i=0; i<this.length; i++) { 
   returnarray.push(this.charcodeat(i)); 
  } 
  return returnarray; 
} 
string.prototype.replaceall = function($old, $snew){   
  return this.replace(new regexp($old,"gm"),$snew);   
} 

变量替换

var a = "i love {0}, and you love {1},where are {0}!";a.format("you","me"); 
string.prototype.format = function(){ 
  var args = arguments; 
  return this.replace(/\{(\d+)\}/g,function(m,i,o,n){ 
    return args[i]; 
  }); 
} 

在字符串末尾追加字符串 

string.prototype.append = function($str){ 
  return this.concat($str); 
} 

删除指定索引位置的字符，索引无效将不删除任何字符 

string.prototype.deletecharat = function($sindex){ 
  if($sindex<0 || $sindex>=this.length){ 
    return this.valueof(); 
  }else if($sindex==0){ 
    return this.substring(1,this.length); 
  }else if($sindex==this.length-1){ 
    return this.substring(0,this.length-1); 
  }else{ 
    return this.substring(0,$sindex)+this.substring($sindex+1); 
  } 
} 

删除指定索引间的字符串.$sindex和$eindex所在的字符不被删除！依赖deletecharat  

string.prototype.deletestring = function($sindex, $eindex){ 
  if($sindex==$eindex){ 
    return this.deletecharat($sindex); 
  }else{ 
    if($sindex>$eindex){ 
      var tindex=$eindex; 
      $eindex=$sindex; 
      $sindex=tindex; 
    } 
    if($sindex<0)$sindex=0; 
    if($eindex>this.length-1)$eindex=this.length-1; 
    return this.substring(0,$sindex+1)+this.substring($eindex,this.length); 
  } 
} 

检查字符串是否以某个字符串(str)结尾 

string.prototype.endswith = function($str){ 
  return this.substr(this.length - $str.length) == $str; 
} 

检查该字符串是否以某个字符串开始 

string.prototype.startswith = function(str){ 
  return this.substr(0, str.length) == str; 
}  

比较两个字符串是否相等，不区分大小写! 

string.prototype.equalsignorecase = function($str){ 
  if(this.length!=$str.length){ 
    return false; 
  }else{ 
    var tmp1=this.tolowercase(); 
    var tmp2=$str.tolowercase(); 
    return tmp1==tmp2; 
  } 
} 

将指定的字符串插入到指定的位置后面!索引无效将直接追加到字符串的末尾 

string.prototype.insert = function($ofset, $str){ 
  if($ofset<0 || $ofset>=this.length-1){ 
    return this.concat($str); 
  } 
  return this.substring(0,$ofset)+$str+this.substring($ofset+1); 
} 

将指定的位置的字符设置为另外指定的字符或字符串.索引无效将直接返回不做任何处理！  

string.prototype.setcharat = function($ofset, $str){ 
  if($ofset<0 || $ofset>=this.length-1){ 
    return this.valueof(); 
  } 
  return this.substring(0,$ofset)+$str+this.substring($ofset+1); 
} 
string.prototype.replacelen = function(start, len, replaced) {  
  if(!len)  
    return this;  
 
  if(start >= this.length)  
    return this;  
 
  var returnseg = '';  
  var returnseg2 = '';  
  var i = 0;  
  for (; i < this.length; i++){  
    var c = this.charat(i);  
    if(i < start)  
      returnseg += c;  
 
    if(i >= start + len)  
      returnseg2 += c;  
  }  
 
  return returnseg + replaced + returnseg2;  
} 

扩展基础类： 
替换字符，这个在替换填入比较有用，比如***天***小时 替换为 <input />天<input />小时  
 

string.prototype.replacechar = function(target, replaced, start) {  
  if(!target)  
    return this;  
  if(!start)  
    start = 0;  
 
  var returnval = this.substring(0, start);  
  var index = 0;  
  for (var i = start; i < this.length; i++) {  
    var c = this.charat(i);  
    target = typeof target == 'function' ? target.call(this, index) : target;  
    if (c == target) {  
      returnval += typeof replaced == 'function' ? replaced.call(this, index) : replaced;  
      while (i < this.length - 1 && this.charat(i + 1) == c) {  
        i++;  
      }  
      index++;  
    }else{  
      returnval += c;  
    }  
  }  
 
  return returnval;  
}  

将该字符串反序排列 

string.prototype.reverse = function(){ 
  var str=""; 
  for(var i=this.length-1;i>=0;i--){ 
    str=str.concat(this.charat(i)); 
  } 
  return str; 
} 

计算长度，每个汉字占两个长度，英文字符每个占一个长度 

string.prototype.uclength = function(){ 
  var len = 0; 
  for(var i=0;i<this.length;i++){ 
    if(this.charcodeat(i)>255)len+=2; 
    else len++; 
  } 
  return len; 
} 

在字符串的左边填充一些特定的字符 

string.prototype.lpad = function(len, s) { 
  var a = new array(this); 
  var n = (len - this.length); 
  for ( var i = 0; i < n; i++) { 
    a.unshift(s); 
  } 
  return a.join(""); 
} 

在字符串的右边填充一些特定的字符 

string.prototype.rpad = function(len, s) { 
  var a = new array(this); 
  var n = (len - this.length); 
  for ( var i = 0; i < n; i++) { 
    a.push(s); 
  } 
  return a.join(""); 
} 

把字符串的首字母转化为大写 

string.prototype.ucwords = function() { 
  return this.substring(0,1).touppercase().concat(this.substring(1)); 
} 
string.prototype.contains = function($str) { 
  return this.indexof($str) > -1 ? true : false; 
} 

将格式为2008-04-02 10:08:44的字符串转成日期(string对象的值必须为: 2008-04-02 10:08:44) 

string.prototype.todate = function(){ 
  var str = this.replace(/-/g,"/"); 
  return (new date(str)); 
} 

将原来用字符串表示的十进数转成十进制浮点数: precision为精度 

string.prototype.tofloat = function(precision){ 
  precision = precision || 2; 
  return parsefloat(this,10).tofixed(precision); 
} 

将原来用字符串表示的十进数转成十进制整数 

string.prototype.toint = function(){ 
  return parseint(this,10).tostring(); 
} 

将两个原来用字符串表示的十进数相加后当作字串返回 : addend为加数 

string.prototype.add = function(addend){ 
  var sum = parsefloat(this,10) + parsefloat(addend,10); 
  return sum+""; 
} 

十进制转其他进制代码如下nextscale为进制 如2,8,16 

string.prototype.shiftscale = function(nextscale){ 
  return parsefloat(this).tostring(nextscale); 
} 

各进制互相转换 ：
this对象必须是整数
@param prescale 原是是几进制数
@param nextscale  要转换成几进制数 
 

string.prototype.scaleshift = function(prescale,nextscale){ 
  return parseint(this,prescale).tostring(nextscale); 
} 

全角2半角 document.write("ａｂｃ　１２３，我们都是好朋友"); 
string.prototype.dbc2sbc = function (){ 
    return this.replace(/[\uff01-\uff5e]/g,function(a){return string.fromcharcode(a.charcodeat(0)-65248);}).replace(/\u3000/g," "); 
} 

array扩展函数：

var isnumeric = function(x) { 
  // returns true if x is numeric and false if it is not. 
  var regexp = /^(-)?(\d*)(\.?)(\d*)$/;  
  return string(x).match(regexp); 
} 
var myarray = [1,'two',3,'four',5,'six',7,'eight',9,'ten']; 
var oddarray=myarray.filter(isnumeric); // outputs: 1,3,5,7,9 
var oddarray=myarray.some(isnumeric); // outputs: true 
var oddarray=myarray.every(isnumeric); // outputs: false 
var printarray =function(x, idx){ 
  document.writeln('['+idx+'] = '+x); 
} 
myarray.foreach(printarray);// outputs: [0] = 1 [1] = two [2] = 3 [3] = four [4] = 5 
myarray.remove(9); 
document.writeln(myarray);  
 
if (!array.prototype.every)  
{ 
 array.prototype.every = function(fun /*, thisp*/) 
 { 
  var len = this.length; 
  if (typeof fun != "function") 
   throw new typeerror(); 
 
  var thisp = arguments[1]; 
  for (var i = 0; i < len; i++) 
  { 
   if (i in this && 
     !fun.call(thisp, this[i], i, this)) 
    return false; 
  } 
 
  return true; 
 }; 
} 
if (!array.prototype.filter) 
{ 
 array.prototype.filter = function(fun /*, thisp*/) 
 { 
  var len = this.length; 
  if (typeof fun != "function") 
   throw new typeerror(); 
 
  var res = new array(); 
  var thisp = arguments[1]; 
  for (var i = 0; i < len; i++) 
  { 
   if (i in this) 
   { 
    var val = this[i]; // in case fun mutates this 
    if (fun.call(thisp, val, i, this)) 
     res.push(val); 
   } 
  } 
 
  return res; 
 }; 
} 
if (!array.prototype.foreach) 
{ 
 array.prototype.foreach = function(fun /*, thisp*/) 
 { 
  var len = this.length; 
  if (typeof fun != "function") 
   throw new typeerror(); 
 
  var thisp = arguments[1]; 
  for (var i = 0; i < len; i++) 
  { 
   if (i in this) 
    fun.call(thisp, this[i], i, this); 
  } 
 }; 
} 
if (!array.prototype.map) 
{ 
 array.prototype.map = function(fun /*, thisp*/) 
 { 
  var len = this.length; 
  if (typeof fun != "function") 
   throw new typeerror(); 
 
  var res = new array(len); 
  var thisp = arguments[1]; 
  for (var i = 0; i < len; i++) 
  { 
   if (i in this) 
    res[i] = fun.call(thisp, this[i], i, this); 
  } 
 
  return res; 
 }; 
} 
if (!array.prototype.some) 
{ 
 array.prototype.some = function(fun /*, thisp*/) 
 { 
  var len = this.length; 
  if (typeof fun != "function") 
   throw new typeerror(); 
 
  var thisp = arguments[1]; 
  for (var i = 0; i < len; i++) 
  { 
   if (i in this && 
     fun.call(thisp, this[i], i, this)) 
    return true; 
  } 
 
  return false; 
 }; 
} 
array.prototype.sortnum = function() { 
  return this.sort( function (a,b) { return a-b; } ); 
} 
<!-- 
var tmp = [5,9,12,18,56,1,10,42,'blue',30, 7,97,53,33,30,35,27,30,'35','ball', 'bubble']; 
var thirty=tmp.find(30);       // returns 9, 14, 17 
var thirtyfive=tmp.find('35');    // returns 18 
var thirtyfive=tmp.find(35);     // returns 15 
var haveblue=tmp.find('blue');    // returns 8 
var notfound=tmp.find('not there!'); // returns false 
var regexp1=tmp.find(/^b/);     // returns 8,20  (first letter starts with b) 
var regexp1=tmp.find(/^b/i);     // returns 8,19,20 (same as above but ignore case) 
--> 
array.prototype.find = function(searchstr) { 
 var returnarray = false; 
 for (i=0; i<this.length; i++) { 
  if (typeof(searchstr) == 'function') { 
   if (searchstr.test(this[i])) { 
    if (!returnarray) { returnarray = [] } 
    returnarray.push(i); 
   } 
  } else { 
   if (this[i]===searchstr) { 
    if (!returnarray) { returnarray = [] } 
    returnarray.push(i); 
   } 
  } 
 } 
 return returnarray; 
} 

随机改变数组的排序 

array.prototype.shuffle = function (){   
  for(var rnd, tmp, i=this.length; i; rnd=parseint(math.random()*i), tmp=this[--i], this[i]=this[rnd], this[rnd]=tmp);  
  return this; 
}   
<!--var myarray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]; 
var yourarray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]; 
document.writeln(myarray.compare(yourarray)); // outputs: true;--> 
array.prototype.compare = function(testarr) { 
  if (this.length != testarr.length) return false; 
  for (var i = 0; i < testarr.length; i++) { 
    if (this[i].compare) {  
      if (!this[i].compare(testarr[i])) return false; 
    } 
    if (this[i] !== testarr[i]) return false; 
  } 
  return true; 
} 

去掉数组中重复的值var a = new array("5","7","7"); a.unique(); 

array.prototype.unique = function() { 
  var data = this || []; 
  var a = {}; //声明一个对象，javascript的对象可以当哈希表用 
  for (var i = 0; i < data.length; i++) { 
    a[data[i]] = true; //设置标记，把数组的值当下标，这样就可以去掉重复的值 
  } 
  data.length = 0;  
   
  for (var i in a) { //遍历对象，把已标记的还原成数组 
    this[data.length] = i;  
  }  
  return data; 
} 
 
array.prototype.addall = function($array) 
{ 
  if($array == null || $array.length == 0) 
    return; 
 
  for(var $i=0; $i<$array.length; $i++) 
    this.push($array[$i]); 
} 
 
array.prototype.contains = function($value) 
{ 
  for(var $i=0; $i<this.length; $i++) 
  { 
    var $element = this[$i]; 
    if($element == $value) 
      return true; 
  } 
 
  return false; 
} 
 
array.prototype.indexof = function($value) 
{ 
  for(var $i=0; $i<this.length; $i++) 
  { 
    if(this[$i] == $value) 
      return $i; 
  } 
 
  return -1; 
} 
if (!array.prototype.lastindexof) 
{ 
 array.prototype.lastindexof = function(elt /*, from*/) 
 { 
  var len = this.length; 
 
  var from = number(arguments[1]); 
  if (isnan(from)) 
  { 
   from = len - 1; 
  } 
  else 
  { 
   from = (from < 0) 
      ? math.ceil(from) 
      : math.floor(from); 
   if (from < 0) 
    from += len; 
   else if (from >= len) 
    from = len - 1; 
  } 
 
  for (; from > -1; from--) 
  { 
   if (from in this && 
     this[from] === elt) 
    return from; 
  } 
  return -1; 
 }; 
} 
array.prototype.insertat = function($value, $index) 
{ 
  if($index < 0) 
    this.unshift($value); 
  else if($index >= this.length) 
    this.push($value); 
  else 
    this.splice($index, 0, $value); 
} 

根据数组的下标来删除元素  
 

array.prototype.removebyindex=function($n) {　  
  if($n<0){　//如果n<0，则不进行任何操作。  
  　　return this;  
  }else{  
    return this.slice(0,$n).concat(this.slice($n+1,this.length));  
  }  
} 

依赖indexof  

array.prototype.remove = function($value) 
{ 
  var $index = this.indexof($value); 
 
  if($index != -1) 
    this.splice($index, 1); 
} 
 
array.prototype.removeall = function() 
{ 
  while(this.length > 0) 
    this.pop(); 
} 
 
array.prototype.replace = function($oldvalue, $newvalue) 
{ 
  for(var $i=0; $i<this.length; $i++) 
  { 
    if(this[$i] == $oldvalue) 
    { 
      this[$i] = $newvalue; 
      return; 
    } 
  } 
} 
 
array.prototype.swap = function($a, $b) 
{ 
  if($a == $b) 
    return; 
 
  var $tmp = this[$a]; 
  this[$a] = this[$b]; 
  this[$b] = $tmp; 
} 
array.prototype.max = function() {  
  return math.max.apply({}, this);  
}  
array.prototype.min = function() {  
  return math.min.apply({}, this);  
}  
array.prototype.splice = function(start, dellen, item){ 
  var len =this.length; 
  start = start<0?0:start>len?len:start?start:0; 
  dellen=dellen<0?0:dellen>len?len:dellen?dellen:len;   
   
  var arr =[],res=[]; 
  var iarr=0,ires=0,i=0; 
   
  for(i=0;i<len;i++){ 
    if(i<start|| ires>=dellen)  arr[iarr++]=this[i]; 
    else { 
      res[ires++]=this[i]; 
      if(item&&ires==dellen){ 
        arr[iarr++]=item; 
      } 
    }   
  } 
  if(item&&ires<dellen) arr[iarr]=item;  
   
  for(var i=0;i<arr.length;i++){ 
    this[i]=arr[i]; 
  } 
  this.length=arr.length; 
  return res; 
} 
array.prototype.shift = function(){ if(!this) return[];return this.splice(0,1)[0];} 

 
分开添加,关键字shallow copy,如果遇到数组，复制数组中的元素 

array.prototype.concat = function(){ 
  var i=0; 
  while(i<arguments.length){ 
    if(typeof arguments[i] === 'object'&&typeof arguments[i].splice ==='function' &&!arguments[i].propertyisenumerable('length')){ 
    // not shallow copy below 
    // array.prototype.concat.apply(this,arguments[i++]); 
      var j=0; 
      while(j<arguments[i].length) this.splice(this.length,0,arguments[i][j++]); 
      i++; 
    } else{ 
      this[this.length]=arguments[i++]; 
    } 
  } 
  return this; 
} 
 
array.prototype.join = function(separator){ 
  var i=0,str=""; 
  while(i<this.length) str+=this[i++]+separator; 
  return str; 
} 
 
array.prototype.pop = function() { return this.splice(this.length-1,1)[0];} 
 
array.prototype.push = function(){  
  array.prototype.splice.apply(this, 
    [this.length,0].concat(array.prototype.slice.apply(arguments))); //这里没有直接处理参数，而是复制了一下 
  return this.length; 
} 
array.prototype.reverse = function(){ 
  for(var i=0;i<this.length/2;i++){ 
    var temp = this[i]; 
    this[i]= this[this.length-1-i]; 
    this[this.length-1-i] = temp; 
  } 
  return this; 
} 
array.prototype.slice = function(start, end){ 
  var len =this.length; 
  start=start<0?start+=len:start?start:0; 
  end =end<0?end+=len:end>len?len:end?end:len; 
       
  var i=start; 
  var res = []; 
  while(i<end){ 
    res.push(this[i++]); 
  } 
  return res;  
} 
//arr.unshift(ele1,ele2,ele3....) 
array.prototype.unshift =function(){ 
  array.prototype.splice.apply(this,[0,0].concat(array.prototype.slice.apply(this,arguments))); 
}