Js：多维数组字面量声明：添加元素

Question

我想知道是否可以将元素添加到声明如下的数组中...请检查 add() 函数，我不知道如何解决这个问题。 谢谢

这不是必需的，但如果您从 C++ 的角度程序员角度给出解释，我将不胜感激。

// My array is this way declared
var myArray = [
    ['John', 'Doe', '1980'],
    ['Jane','Malloy','1982'],
    ['Vincent','Malloy','1972']
];

// then I want to add a new elements in it, but It seems to doesn't work
var add = function() {
    
    //var textbox = document.getElementById('textbox').value;
    
    // storing new person in array
    myArray [3][0] = 'New1';
    myArray [3][1] = 'New2';
    myArray [3][2] = 'New3';
};

//finally this function is for displaying the elements of myArray
var show = function() {

    // clean output
    document.getElementById('output').innerHTML = '';

    // delay time
    setTimeout (function() {

    // showing info. people
        for (var i in myArray) {
            for (var j in myArray)
                document.getElementById('output').innerHTML += myArray[i][j] + ' ';
        
            document.getElementById('output').innerHTML += '<br/>';
        }

    }, 250);
};

Answer 1

所以就在这里：

var add = function() {

    //var textbox = document.getElementById('textbox').value;

    // storing new person in array
    myArray [3][0] = 'New1';
    myArray [3][1] = 'New2';
    myArray [3][2] = 'New3';
};

您不能添加到myArray[3]因为myArray[3]未定义。 您需要先为myArray[3]分配一个空数组：

    myArray [3] = [];
    myArray [3][0] = 'New1';
    myArray [3][1] = 'New2';
    myArray [3][2] = 'New3';

或者更一般地说，假设这个想法是添加到数组的末尾，您可以执行以下操作：

 var idx = myArray.length;
 myArray[idx] = [];
 myArray[idx][0] = "New 1";
 // ...

或者甚至是这样的：

var newArray = ["New1", "New2", "New3"];
myArray.push(newArray);