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Learning JavaScript Data Structures and Algorithms - Third Edition
book

Learning JavaScript Data Structures and Algorithms - Third Edition

by Loiane Avancini
April 2018
Beginner to intermediate content levelBeginner to intermediate
426 pages
10h 19m
English
Packt Publishing
Content preview from Learning JavaScript Data Structures and Algorithms - Third Edition

Declaring the spread and rest operators

In ES5, we can turn arrays into parameters using the apply() function. ES2015 has the spread operator (...) for this purpose. For example, consider the sum function we declared in the previous topic. We can execute the following code to pass the x, y, and z parameters:

let params = [3, 4, 5]; 
console.log(sum(...params)); 

The preceding code is the same as the code written in ES5, as follows:

console.log(sum.apply(undefined, params)); 

The spread operator (...) can also be used as a rest parameter in functions to replace arguments. Consider the following example:

function restParamaterFunction(x, y, ...a) { 
  return (x + y) * a.length; 
} 
console.log(restParamaterFunction(1, 2, 'hello', true, 7)); 

The ...

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Learning JavaScript Data Structures and Algorithms

Learning JavaScript Data Structures and Algorithms

Loiane Avancini

Publisher Resources

ISBN: 9781788623872Supplemental Content