如何访问多维数组中的值？
[英]How to access value in multidimensional array?
问题描述
I have the following code: 
我有以下代码：
<html>
<body>
<div style="background-color: lightblue;" onClick="alert(myArray[0][1])">
this is a div
</div>
<script type="text/javascript">
var myArray = new Array();
myArray[0][0] = 0;
myArray[0][1] = 00012;
myArray[0][2] = 00006;
myArray[1][0] = 1;
myArray[1][1] = 00004;
myArray[1][2] = 00001;
</script>
</body>
</html>
When I click on the div, nothing happens; 当我单击div时，什么也没有发生。 there's no alert. 没有警报。 When I change the inside of alert to a string, such as 'test', however, then the alert box does come up. 但是，当我将警报的内部更改为字符串（例如“ test”）时，警报框就会出现。
What am I doing wrong? 我究竟做错了什么？ How can I get the value of an item in a multidimensional array? 如何获取多维数组中项目的值？
Thanks! 谢谢！
3 个解决方案
解决方案1
2 2012-06-24 00:34:05
Write it out like this: 像这样写出来：
<div style="background-color: lightblue;" onClick="alert(myArray[0][1])">
this is a div
</div>
<script type='text/javascript'>
var myArray = [];
myArray.push([0, 00012, 00006]);
myArray.push([1, 00004, 00001]);
</script>
Edit 编辑
The problem is that when you write this: 问题是当您编写此代码时：
var myArray = new Array();
myArray[0][0] = 0;
The first item in myArray is undefined, so you can't do anything with it. myArray中的第一项是未定义的，因此您无法对其进行任何操作。 Using this method, you'd have to create the array first: 使用此方法，您必须首先创建数组：
var myArray = new Array();
myArray[0] = new Array();
myArray[0][0] = 0;
But I think the method of using the square notation with push is cleaner. 但是我认为将方形符号与push一起使用的方法更加简洁。
解决方案2
2 2012-06-24 00:45:13
This is how you declare a multi dimensional array: 这是您声明多维数组的方式：
MultiArray = new Array(2)
MultiArray [0] = new Array(2)
MultiArray [0][0] = "Tom"
MultiArray [0][1] = "scientist"
MultiArray [1] = new Array(2)
MultiArray [1][0] = "Beryl"
MultiArray [1][1] = "engineer"
解决方案3
2 已采纳 2012-06-24 01:03:51
The first line of your code: 您的代码的第一行：
var myArray = new Array();
...will create a new, single dimensional array, myArray , that has no elements. ...将创建一个没有元素的新的一维数组myArray 。 Then when you say: 然后当你说：
myArray[0][0] = 0;
...you are trying to access a dimension that doesn't exist yet. ...您正在尝试访问一个尚不存在的维度。 That is, myArray[0] is undefined because although myArray is an array it doesn't have any elements yet - so myArray[0][0] is like saying undefined[0] . 也就是说， myArray[0]是undefined因为尽管myArray是一个数组，但还没有任何元素-所以myArray[0][0]就像说undefined[0] 。
That's why you have to to assign myArray[0] to refer to a new array before you can access myArray[0][0] . 这就是为什么在访问myArray[0][0]之前必须分配myArray[0]来引用新数组。 The same thing applies to myArray[1] , because JavaScript doesn't have multi-dimensional arrays per se, it has arrays of arrays. 同样的情况也适用于myArray[1] ，因为JavaScript本身没有多维数组，因此具有数组数组。 So this is what you need (for a minimal change to your existing code): 因此，这就是您所需要的（对现有代码的最小更改）：
var myArray = [];
myArray[0] = [];
myArray[0][0] = 00012;
myArray[0][1] = 00012;
myArray[0][2] = 00006;
myArray[1] = [];
myArray[1][0] = 1;
myArray[1][1] = 00004;
myArray[1][2] = 00001;
Note that [] is equivalent to new Array() . 注意[]等同于new Array() 。
An easier to read and type option is to create the sub-arrays via array literal syntax: 易于阅读和键入的选项是通过数组文字语法创建子数组：
var myArray = [];
myArray[0] = [00012, 00012, 00006];
myArray[1] = [1, 00004, 00001];
Or, easiest of all (especially if these are hard-coded values) is creating the whole thing in one statement via a nested array literal (white-space is ignored): 或者，最简单的方法（尤其是如果这些是硬编码的值）是通过嵌套数组文字（忽略空格）在一个语句中创建整个内容：
var myArray = [
[00012, 00012, 00006],
[1, 00004, 00001]
];
(Note also that those leading zeros will disappear for numeric data: use strings ( "00012" instead of 00012 ) if you want to retain the zeros.) （还请注意，对于数字数据，这些前导零将消失：如果要保留零，请使用字符串（ "00012"而不是00012 ）。）
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