every,some,filter,map数组方法区别

Posted 2021-02-21 changyuqing

/**
* 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
**/

            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)