Lesson 95 +15 XP

String and Array Methods Reference

String and Array Methods Reference

The most useful string and array methods at a glance.

String methods

Method	Purpose
`length`	number of characters
`toUpperCase()`	make uppercase
`toLowerCase()`	make lowercase
`trim()`	remove spaces at ends
`slice(a, b)`	extract a section
`split(sep)`	turn into an array
`includes(text)`	does it contain text
`replace(a, b)`	swap text
`indexOf(text)`	first position or -1

Array methods

Method	Purpose
`length`	number of items
`push(x)`	add at end
`pop()`	remove last
`shift()`	remove first
`unshift(x)`	add at start
`includes(x)`	does it contain x
`indexOf(x)`	position of x or -1
`sort()`	sort items
`join(sep)`	turn into a string
`map(fn)`	transform each item
`filter(fn)`	keep matches
`reduce(fn, init)`	combine into one

split and join

split string to array; join array to string:

"a,b".split(","); // ["a", "b"]
["a", "b"].join(","); // "a,b"

TL;DR

Strings: toUpperCase, split, slice, includes.
Arrays: push, pop, map, filter, reduce.
split and join are opposites.