1     //高阶函数：一个函数可以接受另一个函数作为参数，这种函数称之为高阶函数。 2         /*1*/ 3         function f(x,y,f){ 4             return f(x)+f(y); 5         } 6         var sumAbs=f(-6,4,Math.abs); 7         console.log(sumAbs);//10 8  9 10 11         //map和reduce12         /*map*/13         /*2*/14         function pow(x){15             return x*x;16         }17         var arr=[1,2,3,4,5];18         var x2=arr.map(pow);19         var toS=arr.map(String);20         console.log(x2);//[1, 4, 9, 16, 25]21         console.log(toS);//["1", "2", "3", "4", "5"]22 23 24         /*reduce*/25         /*3*/26         var arr=[1,3,5,7,9];27         function sum(x,y){28             return x+y;29         }30         function pro(x,y){31             return x*y;32         }33         function intt(x,y){34             return x*10+y;35         }36         var s=arr.reduce(sum);37         var p=arr.reduce(pro);38         var i=arr.reduce(intt);39         console.log(s);//2540         console.log(p);//94541         console.log(i);//1357942 43         /*or*/44         console.log(arr.reduce(function(x,y){45             return x+y;46         }));//2547             console.log(arr.reduce(function(x,y){48             return x*y;49         }));//94550             console.log(arr.reduce(function(x,y){51             return x*10+y;52         }));//1357953 54 55         /*string to int*/56         /*4*/57         var str="5678";58         var arr=str.split('');59         console.log(arr);//["5", "6", "7", "8"]60         arr=arr.map(function(x){61             return x-0;62         })63         console.log(arr);//[5, 6, 7, 8]64         console.log(arr.reduce(function(x,y){65             return x*10+y;//567866         }))67 68         /*or*/69         console.log(str.split('').map(function(x){70             return x-0;71         }).reduce(function(x,y){72             return x*10+y;73         }));//567874 75         76         /*请把用户输入的不规范的英文名字，变为首字母大写，其他小写的规范名字。输入：['adam', 'LISA', 'barT']，输出：['Adam', 'Lisa', 'Bart']。*/77 78         /*test*/79         var str="abs";80         console.log(str[0]);//a81         /*5*/82         var arr=['adam', 'LISA', 'barT'];83         console.log(arr.map(function(x){84             return x[0].toUpperCase()+x.substring(1).toLowerCase()85         }));// ["Adam", "Lisa", "Bart"]