在Javascript ES5和ES6中，如何严格影响此关键字在Function对象的调用和应用方法的上下文中

Question

I want know the concept of this in use strict mode , in the context of call and apply method of a Function object in Javascript ES5 and ES6. A good example with explanation will be highly appreciated.

Answer 1

If a function is strict , its this value is not converted to an object but kept as it is. For non-strict functions, this is always converted to an object (unless it is null or undefined of course):

 function foo() { console.log(typeof this); } function foo_strict() { "use strict"; console.log(typeof this); } foo.call(42); foo_strict.call(42);