前端_javascript的利器

• Javascript查询器（数组为例）
• 转载地址(http://www.cnblogs.com/yzp12sina/p/3525098.html)

 Select

遍历元素下的每一个元素,调用JS.Call方法返回数据。

SelectMany 

Array.prototype.selectMany = function (selector, resSelector) {
    resSelector = resSelector || function (i, res) { return res; };
    return this.aggregate(function (a, b, i) {
        return a.concat(selector(b, i).select(function (res) { return resSelector(b, res) }));
    }, []);
}; 

var arr = [{Name:"A", Values:[1, 2, 3, 4]}, {Name:"B", Values:[5, 6, 7, 8]}];  
var res1 = arr.selectMany(function(t){ return t.Values });  
var res2 = arr.selectMany(function(t){ return t.Values }, function(t, u){ return {Name:t.Name, Val:u}});

Take

Array.prototype.take = function (c) {
    return this.slice(0, c);
};  

var arr = [1, 2, 3, 4, 5]; 
var res = arr.take(2);

Array.prototype.skip = function (c) {
    return this.slice(c);
}; 

var arr = [1, 2, 3, 4, 5]; 
var res = arr.skip(2);  

Array.prototype.first = function (predicate, def) {
    var l = this.length;
    if (!predicate) return l ? this[0] : def == null ? null : def;
    for (var i = 0; i < l; i++)
        if (predicate(this[i], i, this))
            return this[i];
    return def == null ? null : def;
}; 

var arr = [1, 2, 3, 4, 5];
var t1 = arr.first();  
var t2 = arr.first(function(t){ return t > 2 }); 
var t3 = arr.first(function(t){ return t > 10 }, 10); //默认值是10

Distinct
找出不重复的数据。当有重复元素是只push一个元素进集合。
Array.prototype.distinct = function (comparer) {
    var arr = [];
    var l = this.length;
    for (var i = 0; i < l; i++) {
        if (!arr.contains(this[i], comparer))
            arr.push(this[i]);
    }
    return arr;
};    


var arr1 = [1, 2, 2, 3, 3, 4, 5, 5];   
var res1 = arr.distinct();  // [1, 2, 3, 4, 5]

var arr2 = [{Name:"A", Val:1}, {Name:"B", Val:1}];
var res2 = arr2.distinct(function(a, b){ return a.Val == b.Val }); //返回[{Name:"A", Val:1}] 

IndexOf

查找指定的值第一次出现的位置。

Array.prototype.indexOf = Array.prototype.indexOf || function (o, index) {
    var l = this.length;
    for (var i = Math.max(Math.min(index, l), 0) || 0; i < l; i++)
        if (this[i] === o) return i;
    return -1;
};  

var arr = [1, 2, 3, 4, 5];
var index = arr.indexOf(2);  // 1 

Remove

Array.prototype.remove = function (item) {
    var i = this.indexOf(item);
    if (i != -1)
        this.splice(i, 1);
}; 

var arr = [1, 2, 3, 4, 5];
arr.remove(2);   // [1, 3, 4, 5]

OrderBy

Array.prototype.orderBy = function (selector, comparer) {
    comparer = comparer || DefaultSortComparer;
    var arr = this.slice(0);
    var fn = function (a, b) {
        return comparer(selector(a), selector(b));
    };

    arr.thenBy = function (selector, comparer) {
        comparer = comparer || DefaultSortComparer;
        return arr.orderBy(DefaultSelector, function (a, b) {
            var res = fn(a, b);
            return res === 0 ? comparer(selector(a), selector(b)) : res;
        });
    };

    arr.thenByDescending = function (selector, comparer) {
        comparer = comparer || DefaultSortComparer;
        return arr.orderBy(DefaultSelector, function (a, b) {
            var res = fn(a, b);
            return res === 0 ? -comparer(selector(a), selector(b)) : res;
        });
    };

    return arr.sort(fn);
}; 
var arr = [{Name:"A", Val:1}, {Name:"a", Val:2}, {Name:"B", Val:1}, {Name:"C", Val:2}];

var res1 = arr.orderBy(function(t){ return t.Name });   

var res2 = arr.orderBy(function(t){ return t.Name }, function(a, b){
    if(a.toUpperCase() > b.toUpperCase()) return 1;
    if(a.toUpperCase() < b.toUpperCase()) return -1;
    return 0;
});    

OrderByDescending

Array.prototype.orderByDescending = function (selector, comparer) {
    comparer = comparer || DefaultSortComparer;
    return this.orderBy(selector, function (a, b) { return -comparer(a, b) });
};

var arr = [{Name:"A", Val:1}, {Name:"a", Val:2}, {Name:"B", Val:1}, {Name:"C", Val:2}];
var res = arr.orderByDescending(function(t){ return t.Name });   

GroupBy

Array.prototype.groupBy = function (selector, comparer) {
    var grp = [];
    var l = this.length;
    comparer = comparer || DefaultEqualityComparer;
    selector = selector || DefaultSelector;

    for (var i = 0; i < l; i++) {
        var k = selector(this[i]);
        var g = grp.first(function (u) { return comparer(u.key, k); });

        if (!g) {
            g = [];
            g.key = k;
            grp.push(g);
        }

        g.push(this[i]);
    }
    return grp;
};  

Where

Array.prototype.where = Array.prototype.filter || function (predicate, context) {
    context = context || window;
    var arr = [];
    var l = this.length;
    for (var i = 0; i < l; i++)
        if (predicate.call(context, this[i], i, this) === true) arr.push(this[i]);
    return arr;
}; 

var arr = [1, 2, 3, 4, 5];
var res = arr.where(function(t){ return t > 2 }) ;  // [3, 4, 5] 

Any

Array.prototype.any = function (predicate, context) {
    context = context || window;
    var f = this.some || function (p, c) {
        var l = this.length;
        if (!p) return l > 0;
        while (l-- > 0)
            if (p.call(c, this[l], l, this) === true) return true;
        return false;
    };
    return f.apply(this, [predicate, context]);
};  

var arr = [1, 2, 3, 4, 5];
var res1 = arr.any();  // true
var res2 = arr.any(function(t){ return t > 5 });  // false 

All

Array.prototype.all = function (predicate, context) {
    context = context || window;
    predicate = predicate || DefaultPredicate;
    var f = this.every || function (p, c) {
        return this.length == this.where(p, c).length;
    };
    return f.apply(this, [predicate, context]);
};  

var arr = [1, 2, 3, 4, 5];
var res = arr.all(function(t){ return t < 6 });  // true 

Contains

Array.prototype.contains = function (o, comparer) {
    comparer = comparer || DefaultEqualityComparer;
    var l = this.length;
    while (l-- > 0)
        if (comparer(this[l], o) === true) return true;
    return false;
}; 

var arr1 = [1, 2, 3, 4, 5]; 
var res1 = arr.contains(2);  // true 

var arr2 = [{Name:"A", Val:1}, {Name:"B", Val:1}]; 
var res2 = arr2.contains({Name:"C", Val:1}, function(a, b){ return a.Val == b.Val }) ;  // true 

ForEach

Array.prototype.forEach = Array.prototype.forEach || function (callback, context) {
    context = context || window;
    var l = this.length;
    for (var i = 0; i < l; i++)
        callback.call(context, this[i], i, this);
};  

var arr = [1, 2, 3, 4, 5];
arr.forEach(function(t){ if(t % 2 ==0) console.log(t); });   

DefaultIfEmpty

Array.prototype.defaultIfEmpty = function (val) {
    return this.length == 0 ? [val == null ? null : val] : this;
};  

var arr = [1, 2, 3, 4, 5];
var res = arr.where(function(t){ return t > 5 }).defaultIfEmpty(5);  // [5]