ES6学习（数组）

数组：

// map 映射，一个对一个

let arr=[2,33,5];

let result=arr.map(item=>item*2);

alert(result);  //4;66;10

let score=[20,76,56,44,88,90];

let result2=score.map(item2=>item2>=60?'及格':'不及格');

alert(result2);

// reduce 汇总 一堆出来一个，如总数

let arr2 = [22,45,22,55,63,12,543,2324];

let result3=arr2.reduce(function(tep,items,index){

// alert(tep+','+items+','+index);

if(index=arr2.length-1){

return tep+items;  //762,2324,7

}else{

return (tep+items)/arr2.length;

}

})

alert(result3); //3086

// filter 过滤器

let arr3=[23,45,676,454,33,4,66];

// var result4= arr3.filter(item3=>{

// if(item3%2==0){

// return true;

// }else{

// return false;

// }

// })

let result4= arr3.filter(item3=>item3%2==0); alert(result4);

let arr4=[

{title:'面包',price:40003},

{title:'火腿肠',price:23},

{title:'香蕉',price:4600},

{title:'例子',price:413}

]

let result5=arr4.filter(json=>json.price>=1000);

console.log(result5);

// forEach 迭代循环

let arr5=[3,2,5,36,7];

// arr5.forEach(item4=>{

// alert(item4);

// });

arr5.forEach((item4,index)=>{

alert(index+':'+item4);

});