ES6 - Arrays

Datetime:2016-08-22 23:01:50          Topic: ECMAScript           Share

Arrays

ES6 brings an abundance of new Array methods:

  • Array: from , of
  • Array.prototype: findIndex() , fill() , find() , copyWithin() , keys() , values() , entries()

Using Array.from we create a new array instance from an array-like or iterable object

var doc = document.querySelectorAll('*');
Array.from(doc).forEach(function(nodes) {
  console.log(nodes);
});

Using Array.of we create an array of variable arguments passed to the function

var arr = Array.of(true, null, undefined, `some message`, 50);
console.log( arr ); //[ true, null, undefined, "some message", 50]

Examples of additional array methods:

// copyWithin()
[1, 2, 3, 4, 5].copyWithin(0, 3); // => [4, 5, 3, 4, 5]

let letters = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J"];
letters.copyWithin(4, 0); // => there is an optional parameter copyWithin(4, 0, 2)
console.log(letters); // ["A", "B", "C", "D", "A", "B", "C", "D", "E", "F"]

// find()
let cities = ["Beirut", "Karachi", "Islamabad", "Athens", "Kabul", "Tapei", "Bucharest"];

let t = cities.find(char => char.endsWith("t"));
console.log( t ); 

// keys()
let people = ["Ahad", "Moe", "Zoey", "Snaey"];

for( let entry of fruits.entries() ) {
  console.log(entry[0]);
  // 0
  // 1
  // 2
  // 3

  console.log(entry[1]);
  // Ahad
  // Moe
  // Zoey
  // Snaey
}




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