1. Lodash

A modern JavaScript utility library delivering modularity, performance & extras.

Many features can be replaced with native ES6 now.

Samples:

• Loop for N times

  _.times(5, (n)=>{console.log(n)});
  // 0
  // 1
  // 2
  // 3
  // 4
  

• Loop through a collection and return a deeply-nested property from each item

  The point is it will handle empty attributes automatically.

  const ownerArr = [{
    "owner": "Colin",
    "pets": [{"name":"dog1"}, {"name": "dog2"}]
  }, {
    "owner": "John",
    "pets": [{"name":"dog3"}, {"name": "dog4"}]
  }, {
    "owner": "John",
  }];
  console.log( _.map(ownerArr, 'pets[0].name') );
  //  [ 'dog1', 'dog3', undefined ]
  

• Create an array of N size and populate them with unique values of the same prefix

  console.log( _.times(6, _.uniqueId.bind(null, 'ball_')) );
  // [ 'ball_1', 'ball_2', 'ball_3', 'ball_4', 'ball_5', 'ball_6' ]
  

• Deep Cloning

  let objA = {
    "name": "colin",
    "obj" : {
      "name": "haha"
    }
  };
  
  let objB = _.cloneDeep(objA);
  objB.obj.name = "ahaha";
  console.log(objB, objA);
  // { name: 'colin', obj: { name: 'ahaha' } } { name: 'colin', obj: { name: 'haha' } }
  

• Get Random Number between a range

  console.log( _.random(15, 20) );
  console.log( _.random(15, 20, true) );
  // 17
  // 17.24617688571962
  

• delete and pick array attributes

  let obj7A = {"name": "colin", "car": "suzuki"};
  console.log( _.omit(obj7A, ['car', 'age']) ); // {"name": "colin"}
  
  let obj8A = {"name": "colin", "car": "suzuki", "age": 17};
  let obj8B = _.pick(obj8A, ['car', 'age']);
  console.log(obj8B);
  
  // { name: 'colin' }
  // { car: 'suzuki', age: 17 }
  

• Random pick elements

  const luckyDraw = ["Colin", "John", "James", "Lily", "Mary"];
  console.log( _.sample(luckyDraw) );
  

• Array Minus

  const obj10A = ["Colin", "John", "James", "Lily", "Mary"];
  const obj10B = ["Lily", "Mary", "Brian"];
  console.log( _.difference(obj10A, obj10B) );
  // [ 'Colin', 'John', 'James' ]
  

https://colintoh.com/blog/lodash-10-javascript-utility-functions-stop-rewriting https://lodash.com/

2. Bluebird

As it says in github page: Bluebird is a full featured promise library with unmatched performance.

Although since ES6 we can use promises without any further thinking, but when it comes to browsers, it is still difficult, especially when we need to support legacy browsers.

So mainly I use it in frontend. However, there are some attractive features, like cancellable promises.

const BPromise = require("bluebird");
BPromise.config({
  // Enable cancellation
  cancellation: true,
});
const proA = new BPromise( (res, rej) => {
  setTimeout( () => {
    res("From Bluebird Promise");
  }, 1000);
});

proA.then( (res) => {
  console.log(res);
})
console.log("normal seq");

const proB = new BPromise( (res, rej) => {
  setTimeout( () => {
    res("never will enter here Bluebird Promise");
  }, 1000);
});

proB.then( (res) => {
  console.log(res);
});
proB.cancel();
console.log("after canceled");

// normal seq
// after canceled
// From Bluebird Promise

http://bluebirdjs.com/docs/why-bluebird.html

3. superagent

• whatwg-fetch (fetch polyfill)
• superagent (IE9+ and Node)
• axios (IE 11+ and Node)
• request (Node)

All these are famous HTTP Client. All is very developer friendly

const superagent = require('superagent');

// callback
superagent
  .get('https://github.com/visionmedia/superagent')
  .then( (res) => {
    console.log(res);
  });

https://medium.com/@kartikag01/fetch-vs-axios-vs-request-promise-vs-superagent-8e78fa358d17