本文小编为大家详细介绍“JavaScript常用字符串与数组扩展函数有哪些”，内容详细，步骤清晰，细节处理妥当，希望这篇“JavaScript常用字符串与数组扩展函数有哪些”文章能帮助大家解决疑惑，下面跟着小编的思路慢慢深入，一起来学习新知识吧。
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)));
}