console.log(this) in global scope returns undefined

Question

I have created a script which logs the this variable to the console in the global scope. If I launch the script in the browser it returns undefined. eg.

console.log(this); //returns undefined

However if I enter the same command directly in the browser console it returns the window object. Which is what I was expecting. eg.

console.log(this); //returns Window {postMessage: ƒ, blur: ƒ, focus: ƒ, close: ƒ, frames: Window, …}

Why is the behavior/output of logging 'this' to the console different in the browser console and different while inspecting the output from a script?

Edit: I am compiling the script with babel (es2015 preset). As far as my initial question is concerned the issue is now resolved. Disabling the Babel preset/plugins results in the expected output of the this variable.

Answer 1

此外，如果您使用的是 ES6 模块，则会自动启用严格模式，如果在全局范围内使用它，它将返回 undefined。