How to delete an element in JS array-JS Tutorial-php.cn

How to delete an element in JS array

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Release： 2018-06-08 10:52:22

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Now I will share with you a JS method to delete an element in an array. It has a good reference value and I hope it will be helpful to everyone.

Delete an element specified in the array

First, you can define a function for the JS array object to find the position of the specified element in the array, that is, the index , the code is:

Array.prototype.indexOf = function(val) { 
for (var i = 0; i < this.length; i++) { 
if (this[i] == val) return i; 
} 
return -1; 
};

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Then use to get the index of this element, and use the js array's own inherent function to delete this element:

The code is:

Array.prototype.remove = function(val) { 
var index = this.indexOf(val); 
if (index > -1) { 
this.splice(index, 1); 
} 
};

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This way Constructed such a function, for example, I have an array:

var emp = [&#39;abs&#39;,&#39;dsf&#39;,&#39;sdf&#39;,&#39;fd&#39;]

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If we want to delete the 'fd' in it, we can use:

emp.remove(&#39;fd&#39;);

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Deleted array An item of

splice(index,len,[item]) Note: This method will change the original array.

splice has 3 parameters, it can also be used to replace/delete/add one or several values in the array

index: array starting subscript len: replacement/delete length item :Replacement value, if the delete operation is performed, the item will be empty

For example: arr = ['a','b','c','d']

Delete

//删除起始下标为1，长度为1的一个值(len设置1，如果为0，则数组不变) 
var arr = [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;]; 
arr.splice(1,1); 
console.log(arr); 
//[&#39;a&#39;,&#39;c&#39;,&#39;d&#39;]; 
 
 
//删除起始下标为1，长度为2的一个值(len设置2) 
var arr2 = [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;] 
arr2.splice(1,2); 
console.log(arr2); 
//[&#39;a&#39;,&#39;d&#39;]

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Replace

//替换起始下标为1，长度为1的一个值为‘ttt&#39;，len设置的1 
var arr = [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;]; 
arr.splice(1,1,&#39;ttt&#39;); 
console.log(arr);   
//[&#39;a&#39;,&#39;ttt&#39;,&#39;c&#39;,&#39;d&#39;] 
 
 
var arr2 = [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;]; 
arr2.splice(1,2,&#39;ttt&#39;); 
console.log(arr2);   
//[&#39;a&#39;,&#39;ttt&#39;,&#39;d&#39;] 替换起始下标为1，长度为2的两个值为‘ttt&#39;，len设置的1

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Add----len is set to 0, item is the added value

var arr = [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;]; 
arr.splice(1,0,&#39;ttt&#39;); 
console.log(arr);   
//[&#39;a&#39;,&#39;ttt&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;] 表示在下标为1处添加一项&#39;ttt&#39;<span style="font-size:14px;font-family:Arial, Helvetica, sans-serif;background-color:rgb(255,255,255);"> </span>

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After the delete method deletes the elements in the array, it will set the subscripted value to undefined, and the length of the array will not change.

var arr = [&#39;a&#39;,&#39;b&#39;,&#39;c&#39;,&#39;d&#39;]; 
delete arr[1]; 
arr; 
//["a", undefined × 1, "c", "d"] 中间出现两个逗号，数组长度不变，有一项为undefined

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The above is what I compiled for everyone. I hope it will be helpful to everyone in the future. .

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