every,some,filter,map数组方法区别
/**
* every()遍历数组,判断是否全部符合条件,只有全部满足才返回true,否则就false
* some()遍历数组,判断是否有符合的,有一个符合就返回true,不再往后执行,和every相反
* filter()遍历数组,判断是否有符合的,返回符合条件的数据组成的数组,不改变原数组
* map()遍历数组,判断是否有符合条件的,返回数组,数组由true和false组成,不改变原数组
*reduce(pre.current,index)数组数据累加,pre上次累加的结果值,current当前待加的数值
**/
let array=[1,2,4,7,9] , newArray=[] ; let checNum =(current)=>current<2; // console.log("newArray:",array.every(checNum)); console.log("newArray:",array.every(function(val){ console.log("vevery-al:",val); return val>1; })); // console.log("array",array); console.log("some:",array.some(checNum)); console.log("some:",array.some(function(value){ console.log("some-value:",value); return value>1; })); console.log("filter:",array.filter(checNum)); console.log("filter:",array.filter(function(value){ console.log("filter-value:",value); return value>1; })); console.log("map:",array.map(function(value){ console.log("map-value",value); return value>2; })); console.log(array)