require.js:
content.js
define('content.js', function(){ return 'A cat';})
index.js
require(['./content.js'], function(animal){
console.log(animal); //A cat
})
commonJS
index.js
var animal = require('./content.js')
content.js
module.exports = 'A cat'
ES6的写法
index.js
import animal from './content'
content.js
export default 'A cat'