dojo 学习日记 之 数组操作

dojo 对Javascript1.6 的数组操作功能进行了拓展：

• clearCache()
• every(arr,callback,thisObject) Determines whether or not every item in arr satisfies the condition implemented by callback.
• filter(arr,thisObject) Returns a new Array with those items from arr that match the condition implemented by callback.
• forEach(arr,thisObject) for every item in arr,callback is invoked.
• indexOf(arr,value,fromIndex,findLast) locates the first index of the provided value in the passed array.
• lastIndexOf(arr,fromIndex) locates the last index of the provided value in the passed array.
• map(arr,thisObject,Ctr) applies callback to each element of arr and returns an Array with the results
• some(arr,thisObject) Determines whether or not any item in arr satisfies the condition implemented by callback.

1.every(arr,thisObject); 校验是否数组arr内的所有元素都满足回调函数的条件，是返回true

Parameter	Type	Description
arr	Array | String	用来迭代的数组. 如果是string，则对string的没资格字符操作
callback	Function | String	回调函数被触发，三个参数: item,index,and array ，如果条件满足，返回为true
thisObject	Object	可选 可能作为回调函数的作用域

// returns false
array.every([1,2,3,4],function(item){ return item>1; });

// returns true
array.every([1,function(item){ return item>0; });

2.filter(arr,thisObject) ; 返回一个满足过滤条件元素组成的数组

Parameter	Type	Description
arr	Array	the array to iterate over.
callback	Function | String	a function that is invoked with three arguments (item,array). The return of this function is expected to be a boolean which determines whether the passed-in item will be included in the returned array.
thisObject	Object	Optional may be used to scope the call to callback

// Example
// returns [2,4]
array.filter([1,function(item){ return item>1; });

3.forEach(arr,thisObject) 对arr 的每一个元素，触发回调函数

// log out all members of the array:
array.forEach(
[ "thinger","blah","howdy",10 ],function(item){
console.log(item);
}
);

// log out the members and their indexes
array.forEach(
[ "thinger",function(item,idx,arr){
console.log(item,"at index:",idx);
}
);

// use a scoped object member as the callback
 
var obj = {
prefix: "logged via obj.callback:",callback: function(item){
console.log(this.prefix,item);
}
};

// specifying the scope function executes the callback in that scope
array.forEach(
[ "thinger",obj.callback,obj
);

// alternately,we can accomplish the same thing with lang.hitch()
array.forEach(
[ "thinger",lang.hitch(obj,"callback")
);

4.indexOf(arr,findLast) 从fromIndex 起，返回arr数组中第一次出现value的索引值.

Parameter	Type	Description
arr	Array
value	Object
fromIndex	Integer	Optional
findLast	Boolean	Optional Makes indexOf() work like lastIndexOf(). Used internally; not meant for external usage.

5.map(arr,Ctr) 根据回调函数映射数组值

Parameter	Type	Description
arr	Array | String	the array to iterate on. If a string,operates on individual characters.
callback	Function | String	a function is invoked with three arguments,(item,array),and returns a value
thisObject	Object	Optional may be used to scope the call to callback
Ctr	undefined

// returns [2,4,5]
array.map([1,function(item){ return item+1 });

6.some(arr,thisObject) 检验数组里是否有满足回调函数条件，有则返回true

Parameter	Type	Description
arr	Array | String	the array to iterate over. If a string,operates on individual characters.
callback	Function | String	a function is invoked with three arguments: item,and array and returns true if the condition is met.
thisObject	Object	Optional may be used to scope the call to callback

// is true
array.some([1,function(item){ return item>1; });

// is false
array.some([1,function(item){ return item<1; });