How to input a two-dimensional array in javascript (two ways)

When writing programs using Javascript, two-dimensional arrays are very common when processing matrices, tables and other data, so it is very important to master how to correctly input two-dimensional arrays.

In Javascript, a two-dimensional array usually refers to an array composed of array elements. In other words, each element of an array is an array. When inputting a two-dimensional array, we can use the following two methods.

First way: using nested arrays

By nesting arrays, we can easily input a two-dimensional array. Here is an example code for inputting a 2D array using nested arrays:

var arr = [[1,2,3],[4,5,6],[7,8,9]];

This will create a 2D array of size 3x3, where each element is an array of 3 elements.

We can also add or delete elements in the two-dimensional array as needed. For example, if you want to change the elements of the second row to [10,11,12], you can modify the code to:

var arr = [[1,2,3],[10,11,12],[7,8,9]];

Similarly, if you want to delete the third element, you can modify the code to:

var arr = [[1,2,3],[4,5,6],[8,9]];

Second way: Use loop input

If we need to dynamically input a two-dimensional array, or want to calculate or modify a two-dimensional array in code, we can use loop input Two-dimensional array. Here is an example code that uses a loop to input a 2D array:

var arr = new Array(3);   // 创建一个大小为3的一维数组
for(var i=0;i<arr.length;i++) {
    arr[i] = new Array(3);  // 对于每个元素，创建一个大小为3的一维数组
    for(var j=0;j<arr[i].length;j++) {
        arr[i][j] = i*3+j+1;   // 输入每个元素的值
    }
}

This will create a 2D array of size 3x3, where the value of each element is calculated from i and j. In this example, we use two loops to input the elements of a 2D array. The outer loop traverses the one-dimensional array, and the inner loop traverses the elements in each one-dimensional array element.

When using the loop method to input a two-dimensional array, we can freely combine according to our own needs. For example, if you want to change the code to input a two-dimensional array of size 4x2, you can modify the code to:

var arr = new Array(4);    // 创建一个大小为4的一维数组
for(var i=0;i<arr.length;i++) {
    arr[i] = new Array(2);    // 对于每个元素，创建一个大小为2的一维数组
    for(var j=0;j<arr[i].length;j++) {
        arr[i][j] = i*2+j+1;    // 输入每个元素的值
    }
}

Summary

In Javascript programming, two-dimensional arrays are a very important Data type, it can be used to process multi-dimensional data such as matrices and tables. When inputting a two-dimensional array, we can use nested arrays or loops to input. Either way, mastering the correct input method will make it easier to process and modify two-dimensional arrays.

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