What does render:h = h (App) mean?

When learning Vue.js, a Vue project was created with VUE-CLI, and a line of code in the Main.js file did not know what it meant. Search online to get the following answers:

Reference one: https://www.cnblogs.com/longying2008/p/6408753.html

Reference two: https://www.cnblogs.com/whkl-m/p/6970859.html

Main.js File Contents

Import vue from ' Vue ' import App from './app ' Vue.config.productionTip = False    //Set False to prevent Vue from generating production tips at startup */ Eslint-disable no-new */New Vue ({  el: ' #app ',  render:h = h (APP)    })

Note:/* eslint-disable no-new * * This is not a comment, in JS, the new object needs to be assigned to a value (variable), when instantiated with Vue, do not need to assign a value (variable), so you need to assign a rule to the new This line of code in Vue adds this comment, skipping the check of this code rule through eslint-disable. is one of the common techniques of eslint.

Anyway

Render:h = h (App)   This is an arrow function is affirmative, that corresponds to the es5 form is what???

As follows:

{   render:h = h (App)}

Equivalent to:

{   render:h =>{        return H (App)    }}

Equivalent to:

{    render:function (h) {        return H (App);    }}

That

{    render:function (createelement) {        return createelement (APP);}    }

createelement parameters

Actually read the official document of createelement, I still do not understand createelement usage. How many parameters do the CreateElement method have? What are the meanings and types of each parameter?

Cases:

<! DOCTYPE html>
　　
What does render:h = h (App) mean?