lodash--collection

演示版本：4.8.2

1.countBy

_.countBy([6.1,5.2,6.2],Math.floor);
//{ '5': 1, '6': 2 }

2.event

_.every([1,'123'],Boolean);
//true

_.every([1,0,'123'],Boolean);
//false

3.filter

var filter_model=[
    {'user':'xiaoMing','age':23,'active':true},
    {'user':'xiaoWang','age':21,'active':false}
];
_.filter(filter_model,function(o){
    return !o.active;
});
//[ { user: 'xiaoWang', age: 21, active: false } ]

4.find

var find_model=[
    {'user':'xiaoMing','age':23,'active':true},
    {'user':'xiaoWang','age':21,'active':false},
    {'user':'xiaoXu','age':21,'active':false}
];
//注意，find返回第一个匹配到的对象
_.find(find_model,'active');
//{ user: 'xiaoMing', age: 23, active: true }

5.findLast

var findLast=_.findLast([1,2,3,4],function(obj){
    return obj%2==1;
});
//3  注意：和find一样，也是返回第一个匹配到的对象

6.flatMap

function flatMap_duplicate(n){
    return [[n,n+1]]
}
_.flatMap([1,2],flatMap_duplicate);
//[ [ 1, 2 ], [ 2, 3 ] ]

7.flatMapDeep

function flatMapDeep_duplicate(n){
    return [[n,n+1]]
}
_.flatMapDeep([1,2],flatMapDeep_duplicate);
//[ 1, 2, 2, 3 ]

8.flatMapDepth

function flatMapDepth_duplicate(n){
    return [[[n,n+1]]]
}
_.flatMapDepth([1,2],flatMapDepth_duplicate,2);
//[ [ 1, 2 ], [ 2, 3 ] ]

_.flatMapDepth([1,2],flatMapDepth_duplicate,3);
//[ 1, 2, 2, 3 ]

9.forEach

var forEach=_([1,2]).forEach(function(a){
    console.log(a)
});//记录每个值从左到右,并返回数组
/*
 1
 2
 [ 1, 2 ]
 */
var forEach_2=_.forEach({'name':'me','age':23},function(v,k){
    console.log(k);
});//迭代的顺序不能保证
/*
 name
 age
 { name: 'me', age: 23 }
*/

10.forEachRight

var forEachRight=_.forEachRight([1,2],function(obj){
    console.log(obj);
});
/*
 2
 1
 [ 1, 2 ]
*/

11.groupBy

_.groupBy([4.1,4.2,5.3],Math.floor);
//{ '4': [ 4.1, 4.2 ], '5': [ 5.3 ] }

12.includes

_.includes([1,2,3],1);
//true

_.includes([1,2,3],1,1);
//false

_.includes({'name':'me','age':23},23);
//true

13.invokeMap

_.invokeMap([[5,1,7],[8,6,7]],'sort');
//[ [ 1, 5, 7 ], [ 6, 7, 8 ] ]

14.keyBy

_.keyBy(keyBy_model,'dir');
/*
 { left: { dir: 'left', code: 97 },
 right: { dir: 'right', code: 100 } }
*/