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angular forEach方法遍历源码解读

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angular,forEach

angular中提供了forEach()方法用于遍历对象或数组,供大家参考,具体内容如下

function forEach(obj, iterator, context) { var key, length; if (obj) {  if (isFunction(obj)) {   for (key in obj) {    // Need to check if hasOwnProperty exists,    // as on IE8 the result of querySelectorAll is an object without a hasOwnProperty function    if (key != 'prototype' && key != 'length' && key != 'name' && (!obj.hasOwnProperty || obj.hasOwnProperty(key))) {     iterator.call(context, obj[key], key, obj);    }   }  } else if (isArray(obj) || isArrayLike(obj)) {   var isPrimitive = typeof obj !== 'object';   for (key = 0, length = obj.length; key < length; key++) {    if (isPrimitive || key in obj) {     iterator.call(context, obj[key], key, obj);    }   }  } else if (obj.forEach && obj.forEach !== forEach) {    obj.forEach(iterator, context, obj);  } else if (isBlankObject(obj)) {   // createMap() fast path --- Safe to avoid hasOwnProperty check because prototype chain is empty   for (key in obj) {    iterator.call(context, obj[key], key, obj);   }  } else if (typeof obj.hasOwnProperty === 'function') {   // Slow path for objects inheriting Object.prototype, hasOwnProperty check needed   for (key in obj) {    if (obj.hasOwnProperty(key)) {     iterator.call(context, obj[key], key, obj);    }   }  } else {   // Slow path for objects which do not have a method `hasOwnProperty`   for (key in obj) {    if (hasOwnProperty.call(obj, key)) {     iterator.call(context, obj[key], key, obj);    }   }  } } return obj;}

官方描述:

forEach方法可以遍历数组或对象,函数有三个参数为别为:value,key,obj。
1)、value value指当遍历的对象或数组元素当前的值
2)、 key 是对象属性的的key或者数组的索引
3)、 obj obj即被遍历的对象或数组本身

示例:

   var values = {name: 'misko', gender: 'male'};   var log = [];   angular.forEach(values, function(value, key) {    this.push(key + ': ' + value);   }, log);

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