JS 实现函数重载

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/**
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 * 创建函数重载
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 * @param  {...any} args  参数
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 * @returns 
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 */
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function createOverload(...args) {
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    const callMap = new Map()
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    function overload(...args) {
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        const key = args.map(arg=> typeof arg).join(',')
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        const fn = callMap.get(key)
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        if(fn) {
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            return fn.apply(this, args)
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        }
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        throw new TypeError('fn not found')
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    }
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    overload.addImpl = function(...args) {
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        const fn = args.pop()
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        if(typeof fn !== 'function') {
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            throw new TypeError('fn must be a function')
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        }
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        callMap.set(args.join(','), fn)
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    }
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    return overload
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}
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/**
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 * Tests
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 * 
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 */
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function test(index) {
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    console.log('index:',index)
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}
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const testOverload = createOverload()
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testOverload.addImpl('number',test)
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testOverload.addImpl('string',(name)=>{
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    console.log("name:",name);
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})
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testOverload.addImpl('string','string',(name,sex)=>{
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    console.log("name：",name,"sex：",sex);
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})
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testOverload(10)
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testOverload('老六')
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testOverload('张三','男')

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index: 10
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name: 老六
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name： 张三 sex： 男