为什么false ==“false”是假的？

Question

I am still learning the basics of javaScript and I don't understand why this happens.

Having type coercion false == "false" would be converted into:

false == false //true

or

"false" == "false" //true

So, why false == "false" is false?

Answer 1

You've misunderstood the type conversion rules . false doesn't get converted to a string before comparison.

If Type(x) is Boolean, return the result of the comparison ToNumber(x) == y.

false is converted to a number, which gives:

+0 == "false"

… then …

If Type(x) is Number and Type(y) is String, return the result of the comparison x == ToNumber(y).

… "false" is converted to a number, which gives:

+0 == NaN

… which is false.

Answer 2

The answer is because "false" is a string (as Gerardo Furado pointed out in the comments), the test you are making is equivalent to false = "hello".

Javascript does not look at the word in the string to determine if it is a boolean and then try to get the value from that.

Note:

In general in javascript it is now preferred that you use the === operator, to avoid all of this.

Answer 3

false == "false" // false

因为，布尔值false被转换为0，因此，我们将0与“false”进行比较，输出为false

Answer 4

These are different kind of items. "string" and boolean .

So:

false.toString() == "false"