where the resolve and reject variable or function is defined?

Question

I study angualr ,and I find some code like this:

function asyncFunc() {

return new Promise((resolve, reject) => { // (A)
    setTimeout(() => resolve('DONE'), 100); // (B)
});

}

I want to know where the function resolve and reject is defined? in all the demo,the author has not defined the function.it must be defined somewhere in angular core library.How can I find the source code that defined the two function?

Answer 1

Well firstly it has nothing to do with Angular. It is the Promise object, which is now implemented on most modern browsers. You can also use a polyfill or other similar implementations.

The Promise constructor takes a function and passes it two arguments. They are functions known as "resolve" and "reject". But you can name them whatever you like. In a nutshell, it is the parameters that are used inside a function.

Answer 2

emmm 你可以先看一下ES6的语法Promise

Answer 3

thanks