为什么（true> null）总是在JavaScript中返回true？

Question

有人可以告诉我为什么以下代码在JavaScript中返回true？

console.log(true > null); //returns true

Answer 1

null is like false in this case, wich is 0 as a number. true is 1 as a number.

1 is bigger ( > ) than 0 .

Answer 2

They are converted to numbers, null gives 0 and true gives 1

http://ecma-international.org/ecma-262/5.1/#sec-11.8.5

If it is not the case that both Type( px ) is String and Type( py ) is String, then

1. Let nx be the result of calling ToNumber( px ). Because px and py are primitive values evaluation order is not important.
2. Let ny be the result of calling ToNumber( py ).

Number(null) //0
Number(true) //1

Answer 3

可能是因为true = 1 ，其中null = 0

Answer 4

JavaScript does a lot of type coercion in the background and a lot of the results you'll find aren't useful (see http://wtfjs.com/ ).

In this case, true which is coerced as 1 is greater than null which is coerced to 0. Since 1 is greater than 0 the result is true.

If one of the operands is Boolean, the Boolean operand is converted to 1 if it is true and +0 if it is false.

From the MDN .

Answer 5

What's happening behind is that the relational operators ( > in this case) perform type coercion before doing the comparison. When doing the ToPrimitive , true gets coerced to a 1, and null to a 0. You can check details here of how the operators actually work here

Answer 6

代码不正确，您需要这样做：

console.log(true > typeof null);

Answer 7

The compare operator ">" forces both it's left and right side to be converted to numbers. Number(true) is 1, Number(null) is 0, so what is in the paranthesis is taken as "1>0", which is always true in result.