Tips for creating two-dimensional arrays in JavaScript

Creation of a two-dimensional array in Js:

First of all, JavaScript only supports one-dimensional arrays, but we can implement matrices and multidimensional arrays through some methods.

There are no problems with the normal creation method:

(1) Create a two-dimensional array by nesting a one-dimensional array:

let arr = [] ;
a[0] = [1,2,3,4,5,6];
a[1] = [10,20,30,40,50,60]

Then use a double for loop to iterate over the elements in this two-dimensional array

So using this method to create a multidimensional array, no matter how many dimensions there are, you can traverse it through nested loops

Methods for encountering problems:

  let arr1 = new Array(10).fill(new Array(10).fill(0))

The console prints arr1 :

At this time, if you want to set arr[0][0] = 1 , you will find that the first item of all sub-arrays of the two-dimensional array is changed to 1.

reason:

In summary, it is better to choose an honest creation method:

var a = new Array();

for(var i=0;i<5;i++){ //The length of one dimension is 5

    a[i] = new Array();

    for(var j=0;j<5;j++){ //The length of the two-dimensional is 5

    	a[i][j] = 0;
   }

}

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