为什么数组等于其对应的字符串? [英] Why are arrays equal to their corresponding strings?

问题描述

为什么将数组与对应的字符串进行比较后将其评估为true?

Why is an array evaluated to true when it is compared to its corresponding string?

var a = [1,2,3];
var b = '1,2,3';

console.log(a==b);// true

变量a存储为其分配的数组的内存地址.那么内存地址如何等于该数组的相应字符串.

Variable a stores the memory address of the array it is assigned. Then how is a memory address equal to corresponding string of that array.

推荐答案

在出现"=="的情况下，数组将转换为toString，然后由于松散比较而进行比较，因此它等于true.那么会发生什么:

Well in case of "==", array is converted to toString and then compared due to loose comparison, so it equates to true. So what happens is this:

  var a = [1,2,3];
  var b = '1,2,3';

  a == b //is same as
  a.toString() === b //true

如果要在严格模式下评估为true，则还可以执行以下操作:

If you want to evaluate to true in a strict mode, you may also do something like this:

var a = [1,2,3];
var b = '1,2,3';

a = a.join(',')

console.log(b === a);

每当您比较宽松时(用'=='进行比较)，javascript解释器都会尽力将这两个值转换为通用类型并进行匹配.要引用 MDN

Whenever you're loose comparing (with '=='), javascript interpreter tries it best to to convert both values to a common type and match them. To quote MDN

松散相等将两个值进行转换后进行比较 值转换为通用类型.转换后(一侧或两侧可能 进行转换)，执行最终的相等比较 完全像===一样执行.

Loose equality compares two values for equality, after converting both values to a common type. After conversions (one or both sides may undergo conversions), the final equality comparison is performed exactly as === performs it.

现在你的困惑是

a中存储的变量是数组的内存地址.因此，在第一个代码段中，您说a == b与a.toString == b相同，但是a中的内容是一个内存地址，因此当内存地址转换为字符串时，它与数组的对应字符串如何相等?

好吧，在比较两个变量时，请注意，您不是在比较它们的内存地址，而是在它们存储的值:)因此，不是内存地址被转换为toString而是存储在它.

Well, note here when you comparing two variables, you're not comparing the memory address of them but the values stored at them :) So it's not the memory address that is getting converted to toString but the value stored at it.

此外，这种想法还有一个缺陷.

Also, there's one more flaw in this thinking.

考虑，

        var a = 4, // a holds address of variable a
        b =4; //b holds the address of variable b

现在，这两个变量肯定持有不同的内存地址，因此它们不会等同于true，这是不正确的.我希望你明白了.

Now, these two variables are definitely holding different memory addresses so they wouldn't have been equated to true which is not true. I hope you got the point.

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