JavaScript中迭代器

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js中有很多有用的迭代器：

forEach：不生成新数组

map：生成新数组

var number=[1,5,3,4,5,3,6,7,8,9];number.forEach(function(a){    console.log(a*2);                         // 2106810612141618});var box=number.map(function(a){    alert(a*2);                                //2106810612141618    return a*2;});console.log(box);                             //[2, 10, 6, 8, 10, 6, 12, 14, 16, 18]

every：不生成新数组

filter：生成新数组

var number=[1,5,3,4,5,3,6,7,8,9];var box1=number.every(function(a){    return a>2;                              });var box2=number.filter(function(a){    return a>2;});alert(box1);                             //falsealert(Array.isArray(box2));              //truealert(box2);                             //5,3,4,5,3,6,7,8,9

some

var number=[1,5,3,4,5,3,6,7,8,9];alert(number.some(function(a){    return a>2;}));                                       //true

reduce和reduceRight

var number=[1,5,3,4,5,3,6,7,8,9];alert(number.reduce(function(a,b){    return ''+a+b;}));                                           //1534536789alert(number.reduceRight(function(a,b){    return ''+a+b;}));                                          //9876354351

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