LinqJs

use linq and lambda in javascript 在javascript中使用linq与lambda

在1.0.0中使用了字符串的lambda表达式,过于繁琐,并且不支持延迟操作 Since 2.1.0, I rewrite all to use new features of ES6. The performance be better, memory is used less and using deferred execution. 从2.1.0开始整体代码重新编写,使用全新的ES6的特性,性能更好,同时对数据的操作是延时操作,占用更少

帮助文档(完善中) 👍 Documentation(not completed) 👍

Usage 用法

1. Import 引入

Use NodeJs 使用NodeJs

$ npm install --save linq-js

const Enumerable = require('linq-js');

• description:This module require ES6. I suggest you to use this with ES6. The following examples is already use ES6.
• 说明：本module依赖于ES6。建议项目在中使用ES6。以下案例中将均使用ES6写法。

2. Get IEnumerable instance 获取IEnumerable对象

interface IEnumerable { };

function asEnumerable():IEnumerable;
//You can use the asEnumerable methods of every object's to get an IEnumerable object;
//任何对象都有asEnumerable方法用来获取IEnumerable对象

e.g. 案例

'abc'.asEnumerable();
[1,2,3].asEnumerable();
({a:1,b:2}).asEnumerable();

3. Use IEnumerable instance 使用IEnumerable对象

e.g. 案例

let pets = [ { name: "Barley", age: 8, vaccinated: true }, { name: "Boots", age: 4, vaccinated: false }, { name: "Whiskers", age: 1, vaccinated: false } ];
let unvaccinated = pets.asEnumerable().any(p => p.age > 1 && p.vaccinated === false);
console.log(`There ${ unvaccinated ? "are" : "are not any" } unvaccinated animals over age one.`);
// This code produces the following output: 这段代码输出以下内容：
//  There are unvaccinated animals over age one.

e.g. 案例

let magnus = { name: "Hedlund, Magnus" }, terry = { name: "Adams, Terry" }, charlotte = { name: "Weiss, Charlotte" };
let barley = { name: "Barley", owner: terry }, boots = { name: "Boots", owner: terry }, whiskers = { name: "Whiskers", owner: charlotte }, daisy = { name: "Daisy", owner: magnus };
let people = [ magnus, terry, charlotte ];
let pets = [ barley, boots, whiskers, daisy ];
let query = people.asEnumerable().join(pets,
    (person, pet) => ({ ownerName: person.name, pet: pet.name }),
    person => person,
    pet => pet.owner);
for (let obj of query) {
    console.log(`${ obj.ownerName } - ${ obj.pet }`);
}
/*
 This code produces the following output: 这段代码输出以下内容：
 Hedlund, Magnus - Daisy
 Adams, Terry - Barley
 Adams, Terry - Boots
 Weiss, Charlotte - Whiskers
 */

:see msdn(IEnumerable) :参考 MSDN(IEnumerable)
:see msdn(Enumerable) :参考 MSDN(Enumerable)