Loops in JS

JavaScript has many ways to loop over data structures, depending on what you plan to do with the data inside it, the size of a data structure, as well as the type of data strucutre. In this chapter you'll learn the various ways to execute loops in JS:

• for statement in JS: Explicit counters, iterations, step sizes and performance considerations
• break and continue statements in JS: Exiting for loops and iterations prematurely
• Label statements in JS loops: GoTo a specific point in the workflow of a JS loop
• while and do while statements: Loops that run with one expression
• for in statement: A loop for key-value data structures

Tip Certain JS data types have built-in methods that produce the same outcome as loops with for, while, do while and inclusively for in statements, but with simpler syntax:

• Array loop methods: every(), filter(), forEach(), map(), reduce() & reduceRight()
• Map loop methods: forEach()
• Set loop methods: forEach()

• for of statement: Iterable and iterator protocols, plus what are and how to make iterable objects
• Generators and yield expressions in JS: Functions that operate with iterable objects