Detailed explanation of this in JavaScript arrow function

The arrow function in JavaScript is a relatively new syntax. It does not have its own this keyword. On the contrary, the this of the arrow function points to the scope object containing it. The impacts are: 1. This in the arrow function is Static; 2. Arrow functions cannot be used as constructors; 3. Arrow functions cannot be used as methods.

In JavaScript, the arrow function is a relatively new syntax. It has some differences from ordinary functions. One of the important differences is that the arrow function does not own this keyword. In contrast, the this of an arrow function points to the scope object that contains it (that is, the context in which it is defined).

This feature will have an impact in the following aspects:

1. This in the arrow function is static: because this in the arrow function is bound when it is defined , so it does not change depending on the calling environment. This means that when using arrow functions, you don't need to worry about the pointing problem of this, and you can access variables in the outer scope more conveniently.

2. Arrow functions cannot be used as constructors: Since arrow functions do not have their own this, it means that they cannot be used to create object instances. If you try to use arrow functions to create an object, an error will be thrown.

3. Arrow functions cannot be used as methods: Since the this of arrow functions is static, it does not apply to methods as objects. An arrow function defined on an object binds this to the context in which it is defined rather than the context in which it is called, which can lead to unexpected results.

Summary: The this of a JavaScript arrow function points to the context in which it is defined, not the context when it is called. Its characteristics include static this, cannot be used as a constructor, and cannot be used as a method. When using arrow functions, you need to pay attention to these characteristics to avoid unnecessary errors.

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