Basic usage of js arrays and removing elements from arrays based on subscripts (numeric values ​​or characters)_javascript skills

1. Create an array

Copy the code The code is as follows:

var array = new Array();
var array = new Array(size);//Specify the length of the array
var array = new Array(item1,item2...itemN);//Create an array and assign values

2. Value acquisition and assignment

Copy code The code is as follows:

var item = array[index ];//Get the value of the specified element
array[index] = value;//Assign a value to the specified element

3. Add new elements

Copy code The code is as follows:

array.push(item1,item2...itemN);//Add one or more elements to the array, Return the length of the new array
array.unshift(item1,item2...itemN);//Add one or more elements to the beginning of the array, the original element position will automatically move backward, and return the length of the new array
array.splice(start,delCount,item1,item2...itemN);//Delete delCount elements backward from the start position, and then insert one or more new elements from the start position

4. Delete elements

Copy code The code is as follows:

array.pop() ;//Delete the last element and return the element
array.shift();//Delete the first element, the array element position will automatically move forward, and return the deleted element
array.splice(start, delCount);//Delete delCount elements backward from the start position

5. Merging and intercepting arrays

Copy code The code is as follows:

array.slice(start,end);//Return a part of the array in the form of an array. Note that the element corresponding to end is not included. If it is omitted end will copy all elements after start
array.concat(array1,array2); // Splice multiple arrays into one array

6. Sorting of arrays

Copy code The code is as follows:

array.reverse();//Array reverse
array.sort( );//Array sorting, return array address

7. Convert array to string

Copy code The code is as follows:

array.join(separator);//Connect the arrays with separator

I have listed all of them, but I still can’t find it. Delete the array based on the subscript. Elemental approach! So I checked some information and found a solution.
Deleting array elements requires extending the Array prototype prototype.
Generally, the subscripts of arrays are numerical, but there are also character subscripts.
To process numerical types, first write the following code, It is an extension of array

Copy code The code is as follows:

Array.prototype.del = function (dx)
{
if(isNaN(dx)||dx>this.length){return false;}
this.splice(dx,1);
}

Secondly, numeric parameters can be passed directly. For example, var arr = ["aa","bb"];arr.del(0);
Let’s talk about character subscripts

Copy code The code is as follows:

var arr = [].
arr["aa"] = 1;