$.each([1, 2, 3], function(i, n) {  console.log("當前下標為："+ i + " 當前元素為："+ n );});

var each = function(ary, callback) {  for(var i = 0, l = ary.length; i < l; i++) {    callback.call(ary[i], i, ary[i]);  }  };each([1, 2, 3], function(i, n) {  console.log("當前下標為："+ i + " 當前元素為："+ n );});

[1, 2, 3].forEach(function(n, i, curAry){  console.log("當前下標為："+ i + " 當前元素為："+ n + " 當前數組為：" + curAry);})

// 內部迭代器var each = function(ary, callback) {  for(var i = 0, l = ary.length; i < l; i++) {    callback.call(ary[i], i, ary[i]);  }  };// 比較函數var compareAry = function(ary1, ary2) {  if(ary1.length != ary2.length) {    throw new Error("不相等"); // return console.log("不相等");   }  // 且住  each(ary1, function(i, n) {    if(n !== ary2[i]) {      // return console.log("不相等");       // return 只能返回到each方法外，后續console.log("相等")會繼續執行，所以這里得使用throw      throw new Error("不相等");    }  });  console.log("相等");}compareAry([1, 2, 3], [1, 2, 4]);

// 外部迭代器var Iterator = function(obj) {  var current = 0,    next = function() {      current++;    },    isDone = function() {      return current >= obj.length;      },    getCurrentItem = function() {      return obj[current];    };  return {    next: next,    isDone: isDone,    getCurrentItem: getCurrentItem  };};// 比較函數var compareAry = function(iterator1, iterator2) {  while( !iterator1.isDone() && !iterator2.isDone() ){    if(iterator1.getCurrentItem() !== iterator2.getCurrentItem()) {      throw new Error("不相等");    }    iterator1.next();    iterator2.next();  }  console.log("相等");}compareAry(new Iterator([1, 2, 3]), new Iterator([1, 2, 4]));

var each = function(ary, callback) {  for(var i = 0, l = ary.length; i < l; i++) {    if(callback.call(ary[i], i, ary[i]) === false) {      break;    }  }}each([1, 2, 4, 1], function(i, n) {  if(n > 3) {    return false;  }  console.log(n);});