js array operations pop, push, unshift, splice, shift_javascript skills

<script> <br>Array.prototype.pop=function( ){ <br> if(this.length!=0)this.length--; <br> return this; <br> } <br> </div> <br><strong>pop method <br></strong> Removes the last element from an array and returns that element. <br><br>arrayObj.pop( ) <br><br>The required arrayObj reference is an Array object. <br><br>Explanation <br>If the array is empty, undefined will be returned. <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="32422" class="copybut" id="copybut32422" onclick="doCopy('code32422')"><u>Copy code</u></a></span> The code is as follows:</div> <div class="codebody" id="code32422"> <br>var a=[1,2,3,4] <br>a.pop() <br>alert(a) <br>alert(a.pop())</script><script> <br> </div> <br><strong>push method</strong> <br>Adds a new element to an array and returns the new length of the array. <br><br>arrayObj.push([item1 [item2 [. . . [itemN ]]]]) <br><br>Parameters <br>arrayObj <br><br>Required. An Array object. <br><br>item, item2,. . . itemN <br><br>Optional. The new element of this Array. <br><br> Description The <br>push method will add new elements in the order in which they appear. If one of the arguments is an array, the array is added to the array as a single element. If you want to combine elements from two or more arrays, use the concat method. <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="10396" class="copybut" id="copybut10396" onclick="doCopy('code10396')"><u>Copy code</u></a></span> The code is as follows:</div> <div class="codebody" id="code10396"> <br>Array.prototype.push=function(){ <br> var len=arguments.length; <br> if(len>0)for(var i=0;i<len;i )this[this.length]=arguments[i]; <BR> return this.length; <BR> } <BR>var a=[1,2,3,4] <BR>a.push(5) <BR>alert(a) <BR>alert(a.push(6))</ script><script> <br> </div> <br><strong>unshift method </strong> <br>Inserts the specified element into the beginning of the array and returns the array. <br><br>arrayObj.unshift([item1[, item2 [, . . . [, itemN]]]]) <br><br>Parameters <br>arrayObj <br><br>Required. An Array object. <br><br>item1, item2,. . .,itemN <br><br>Optional. The element to be inserted at the beginning of this Array. <br><br>Explanation The <br>unshift method inserts these elements into the beginning of an array, so these elements will appear in the array in the order of the parameter sequence. <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="49917" class="copybut" id="copybut49917" onclick="doCopy('code49917')"><u>Copy code</u></a></span> The code is as follows:</div> <div class="codebody" id="code49917"> <br>Array.prototype.unshift=function(){    <br>     var len=arguments.length;    <br>     this.reverse();    <br>     if(len>0)for(var i=len;i>0;i--)this[this.length]=arguments[i-1];    <br>     return this.reverse();    <br>     }    <br>var a=[1,2,3,4]    <br>a.unshift()    <br>alert(a)    <br>a.unshift(5,6)    <br>alert(a)    <br>alert(a.unshift(7))</script><script>    <br>Array.prototype.shift=function(){    <br>     var f=this[0];    <br>     for(var i=0;i<this.length;i )this[i]=this[i 1];    <br>     this.length--;    <br>     return f;    <br>     }    <br> </div>   <br><strong>shift 方法</strong>   <br>移除数组中的第一个元素并返回该元素。   <br><br>arrayObj.shift( )   <br><br>必选的 arrayObj 引用是一个 Array 对象。   <br><br>说明   <br>shift 方法可移除数组中的第一个元素并返回该元素。   <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="13600" class="copybut" id="copybut13600" onclick="doCopy('code13600')"><u>复制代码</u></a></span> 代码如下:</div> <div class="codebody" id="code13600"> <br>var a=[1,2]    <br>alert(a.shift())    <br>alert(a)    <br></script>