JavaScript - 数组遍历

for方法

var arr = [1];
for(var i = 0; i < arr.length; i++){
    console.info(arr[i]); //1
}

for...in方法

var arr = [1,2];
for(var index in arr){
    console.info(index,arr[index]); //0 1, 1 2
}

map方法

var arr = [1];
var newArr = arr.map(function(item,index){
    console.info(item,index); //1 0
    return item;
});

forEach方法

var arr = [1];
var newArr = arr.forEach(function(item,index){
    console.info(item,index); //1 0
    return item;
});

filter方法

var arr = [1,2];
var newArr = arr.filter(function(item,index){
    return item > 1;
});
console.info(newArr); //[2]

some方法

var arr = [1,2];
var newArr = arr.some(function(item,index){
    return item > 1;
});
console.info(newArr); //true

every方法

var arr = [1,2];
var newArr = arr.every(function(item,index){
   return item > 1; 
});
console.info(newArr); //false

reduce方法

var arr = [1,2,3];
var total = arr.reduce(function(pre,cur,index,arr){
    console.info(pre); //0,1,3
    return pre + cur;
},0);
console.info(total); //6

reduceRight方法

var arr = [1,2,3];
var total = arr.reduceRight(function(pre,cur,index,arr){
    console.info(pre); //4,5,7
    return pre + cur; 
},4);
console.log(total); //10

for...of方法

var arr = [1,2];
for(var item of arr){
    console.info(item); //1, 2
}