# require

Introduce the module.Return module through module.exports Orexportsexposed interfaces.

When another subcontracted module needs to be introduced, the specified module can be retrieved asynchronously by configuring thecallbackcallback function.When asynchronous fetch fails, theerrorcallback is triggered.

# parameter

name	type	Required to fill in	Introductions
path	string	yes	You need to introduce the relative path of the module file relative to the current file, or the npm module name, or the npm module path.Absolute paths are not supported by default, and custom path maps can be defined by configuring`resolveAlias`.
callback	function	no	Asynchronously load a successful callback function, which parameters are the successfully loaded module.
error	function	no	An asynchronous load failure callback function, which parameters are error message and module name.

# Require.async Chain Call

It can be used by chain call.

require
    .async('path/to/mod')
    .then((mod) => {
        console.log(mod)
    })
    .catch(({ errMsg, mod }) => {
        console.error(`path: ${mod}, ${errMsg}`)
    })

# sample code

# Call within the same package

// common.js
function sayHello(name) {
  console.log(`Hello ${name} !`)
}
function sayGoodbye(name) {
  console.log(`Goodbye ${name} !`)
}

module.exports.sayHello = sayHello
exports.sayGoodbye = sayGoodbye

var common = require('common.js')
Page({
  helloMINA: function() {
    common.sayHello('MINA')
  },
  goodbyeMINA: function() {
    common.sayGoodbye('MINA')
  }
})

# Asynchronous calls across subpackages

// Subpackage / common.js subpackage common file
export const sayHello = () => console.log("hello")

// Pages / index.js main package page

let common;
require('../../subpackage/common.js', (mod) => {
    common = mod
}, ({ errMsg, mod }) => {
    console.error(`path: ${mod}, ${errMsg}`)
})

Page({
    sayHello() {
        common && common.sayHello()
    }
})