函数参数与返回值的学习实例小结 -

函数参数与返回值实例

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    <title>函数参数与返回值实例</title>
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    <script>
        let f=(a,b)=>a+b;
        //正常返回
        console.log(f(10,20));
        //返回NaN：意思是没有一个数值
        console.log(f(10));
        // 1.参数不足的解决办法：默认参数
        f = (a, b = 0) => a + b;
        console.log(f(10,5));
        // 2.参数过多的解决办法：...剩余参数
        f = (a, b) => a + b;
        console.log(f(1,2,3,4,5));
        // 如何将全部参数接收到？剩余参数...
        // ...rest:用在函数的形参中，归并
        f = (a, b, ...c) =>console.log(a,b,c);
        console.log(f(1,2,3,4,5));
        let arr= [1,2,3,4,5];
        console.log(...arr);
        console.log(f(...arr));
        // ...用在函数调用时的实参中是解包
        f=(...arr)=>arr.reduce((a,c)=>a+c);
        console.log(f(1,2,3,4,5,6,7,8,9,10))
        // 返回值：函数只能有一个返回值，默认单值返回
        // 需要返回多个值怎么办
        function fn () {
            return [1,2,3]
        }
        // 简化
        let fn=()=>[1,2,3];
        let res=fn();
        console.log(res);
        fn = () => ({
            id:2,
            name:'admin',
            age:28
        });
        res=fn();
        console.log();
    </script>
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