为什么在 JavaScript 中分配 Infinity 不会引发错误，但不起作用？

Question

Why doesn't infinity give an error when attempted to be reassigned, but is not assignable?

var x = 3;

x = 1; // good, normal
true = 3; // error, normal

Infinity = 4; // no error

console.log(Infinity); // Infinity

Answer 1

As you can read here :

Infinity is a property of the global object, or in other words, a variable in global scope .

Since it's a global property you can access it and assign any value. However assigning a value to a non Writable property doesn't raise any exception, when you are in a not strict mode , and doesn't change the value of the property.

If you use "strict mode", then an exception would be raised.

 "use strict" Infinity = 4;