How to delete an item in an array in es6

Delete method: 1. Use splice() to delete any element based on the subscript, the syntax is "arr.splice(index,1)"; 2. Use the delete keyword to delete any element based on the subscript, the syntax "delete arr[index];"; 3. Use shift() to delete the first element, the syntax is "array.shift()"; 4. Use pop() to delete the last element, the syntax is "array.pop()"; 5. Use length to delete the last element.

The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.

In es6, if you want to delete any item (an element) in the array, you can use the array's splice() method or delete keyword.

Method 1. splice: After deletion, the following elements will be automatically filled in to the front

arr.splice(index, 1)　

Example: Now there are Array arr=['a','b','c','d']

arr.splice(1, 1); //结果arr=['a','c','d']（下标1开始，删除1个）

Note:

In the above code, we should pay attention to that if we want to modify the value of arr, just operate arr directly like this, instead of writing arr= arr.splice(1,1), because the splice() method The return value is the deleted element.

Added:

• spice added:

arr.splice(1,0,'str'); //结果arr=['a','str','b','c','d']

• spice replaced:

arr.splice(1,1,'str'); //结果arr=['a','str','c','d']

• spice Replacement 2:

arr.splice(1,2,'str'); //结果arr=['a','str','d']（就是说：下标1开始2个换成1个“str”）

• spice Delete multiple:

arr.splice(1,2); //结果arr=['a','d']

Method 2, delete: after deletion , the subscript position element is undefined

delete arr[index];

Example:

delete arr[1];

The gap element can be read and written, and the length attribute does not exclude gaps. , the return value of the empty element bit is undefined

console.log(arr[1]);

. If you just want to delete the first or last element, you can also use shift(), pop(), length method.

Method 3: Use the shift() function to delete the first array element

array.shift() function can remove the first element of the array elements are removed from it and the value of the first element is returned; then all remaining elements are shifted forward by 1 position to fill the gap at the head of the array.

var a = [1,2,3,4,5,6,7,8];  //定义数组
a.shift();
console.log(a);

The output result is:

Note: The shift() method will change the original array and modify the length of the array!

Method 4: Use pop() to delete the last array element

array.pop() method can delete the last element in the array , and returns the deleted element.

var a = [1,2,3,4,5,6,7,8];  //定义数组
a.pop();
console.log(a)

The output result is:

Note: The pop() method will also change the original array and modify the length of the array!

Method 5: Use the length attribute to delete the last array element

The length attribute of the array is generally used to set or return the elements in the array Number, that is, setting or returning the array length.

We can take advantage of the feature of setting the length of the array and set the length attribute to be smaller than the original length to delete one or more elements from the end of the array; if the value is set to 0, the entire array will be deleted. That is, clear the array!

Syntax:Array object.length=original array length-1;

Example:

var a = [1,2,3,4,5,6,7,8];  //定义数组
console.log(a)
a.length=7;
console.log(a)

[Recommended learning: javascript advanced tutorial]

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