javascript forEach function implementation code_javascript skills-JS Tutorial-php.cn

javascript forEach function implementation code_javascript skills

WBOY

Release： 2016-05-16 18:37:05

Original

1570 people have browsed it

Copy code The code is as follows:

 
function forEach(object, block, context, fn) { 
 if (object == null) return; 
if (!fn) { 
if (typeof object == "function" && object.call) { 
//Traverse ordinary objects
fn = Function ; 
} else if (typeof object.forEach == "function" && object.forEach != arguments.callee) { 
//If the target has implemented the forEach method, use its own forEach method (such as Array object of standard browser) 
object.forEach(block, context); 
return; 
} else if (typeof object.length == "number") { 
// If it is a class Array object or array object of IE 
_Array_forEach(object, block, context); 
return; 
} 
} 
_Function_forEach(fn || Object, object, block, context); 
}; 
function _Array_forEach(array, block, context) { 
if (array == null) return; 
var i = 0,length = array.length; 
if (typeof array == "string") { 
for (; i < length; i ) { 
block.call(context, array.charAt(i), i, array); 
} 
} else{ 
for (;i < length; i ) { 
block.call(context, array[i], i, array); 
} 
} 
}; 
_Function_forEach = function(fn, object, block, context) { 
// fn here is always Function 
for (var key in object) { 
//Only traverse local properties 
if ( object.hasOwnProperty(key)) { 
//Equivalent to block(object[key], key) 
block.call(context, object[key], key, object); 
} 
 } 
}; 

Some examples from the original author (I jumped over the wall! ):

Copy code The code is as follows:

 
function print(el,index){ 
alert(index " : " el) 
} 
forEach ([1, 2, 3], print); 
forEach ({a: "aa", b: "bb",c: " cc"}, print); 
forEach ("Situ Zhengmei", print); 
forEach(document.styleSheets,function(el){ 
if(el.href) alert(el.href) 
}); 

[Ctrl A Select all Note: If you need to introduce external Js, you need to refresh to execute

]

Copy code

The code is as follows:

 
function Person(name, age) { 
this.name = name || ""; 
this.age = age || 0; 
}; 
Person.prototype = new Person; 
var fred = new Person("Fred", 38); 
fred.language = "English";//Extremely late binding
fred.wife = "Wilma";//Extremely late binding
forEach(fred,print) 

[Ctrl A select all Note:

If you need to introduce external Js, you need to refresh to execute <script> function forEach(object, block, context, fn) { if (object == null) return; if (!fn) { if (typeof object == "function" && object.call) { //遍历普通对象 fn = Function; } else if (typeof object.forEach == "function" && object.forEach != arguments.callee) { //如果目标已经实现了forEach方法，则使用它自己的forEach方法（如标准游览器的Array对象） object.forEach(block, context); return; } else if (typeof object.length == "number") { // 如果是类数组对象或IE的数组对象 _Array_forEach(object, block, context); return; } } _Function_forEach(fn || Object, object, block, context); }; function _Array_forEach(array, block, context) { if (array == null) return; var i = 0,length = array.length; if (typeof array == "string") array = array.split(""); for (;i < length; i++) { block.call(context, array[i], i, array); } }; _Function_forEach = function(fn, object, block, context) { // 这里的fn恒为Function for (var key in object) { //只遍历本地属性 if (object.hasOwnProperty(key)) { //相当于 block(object[key], key) block.call(context, object[key], key, object); } } }; function print(el,index){ alert(index+" : "+el) } forEach ([1, 2, 3], print); forEach ({a: "aa", b: "bb",c: "cc"}, print); forEach ("司徒正美", print); forEach(document.styleSheets,function(el){ if(el.href) alert(el.href) }); </script>]