Operators and strings · Lesson 8 of 45

String methods

Slice, search, replace and clean up text.

8 minutes4 games

Strings come with built-in methods. These are the ones you'll use every day:

Method	What it does	Example
`toUpperCase()` / `toLowerCase()`	upper/lower case	`"hi".toUpperCase()` → `"HI"`
`trim()`	removes spaces at both ends	`" a ".trim()` → `"a"`
`includes(x)`	contains x?	`"cat".includes("a")` → `true`
`startsWith(x)`	starts with x?	`"https".startsWith("http")`
`indexOf(x)`	position of x (or -1)	`"code".indexOf("d")` → `2`
`slice(a, b)`	part from a up to b	`"SeaCode".slice(0, 3)` → `"Sea"`
`split(sep)`	splits into an array	`"a,b".split(",")`
`replaceAll(a, b)`	replaces every a with b	`"1-2-3".replaceAll("-", "/")`
`padStart(n, c)`	pads to length n	`"7".padStart(2, "0")` → `"07"`

JavaScript

const email = "  Ahmed@SeaCode.tech "
const clean = email.trim().toLowerCase()
console.log(clean)
console.log(clean.includes("@"))
console.log(clean.split("@"))
console.log(clean.slice(0, clean.indexOf("@")))

const time = "9:5"
const [h, m] = time.split(":")
console.log(`${h.padStart(2, "0")}:${m.padStart(2, "0")}`)

You can chain methods: trim().toLowerCase().

What's the output?

console.log("JavaScript".slice(0, 4))

What will this code print?

Complete the code

Split the text at every comma.

const tags = "html,css,js"
console.log(tags.(","))

Spot the bug

This code checks the email has an @. Where's the mistake?

Exercise

Reverse "seacode" and print it (edocaes).

Expected output: edocaes

JavaScript

const word = "seacode"

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JavaScript

Operators and strings · Lesson 8 of 45

String methods

Slice, search, replace and clean up text.

8 minutes4 games

Strings come with built-in methods. These are the ones you'll use every day:

Method	What it does	Example
`toUpperCase()` / `toLowerCase()`	upper/lower case	`"hi".toUpperCase()` → `"HI"`
`trim()`	removes spaces at both ends	`" a ".trim()` → `"a"`
`includes(x)`	contains x?	`"cat".includes("a")` → `true`
`startsWith(x)`	starts with x?	`"https".startsWith("http")`
`indexOf(x)`	position of x (or -1)	`"code".indexOf("d")` → `2`
`slice(a, b)`	part from a up to b	`"SeaCode".slice(0, 3)` → `"Sea"`
`split(sep)`	splits into an array	`"a,b".split(",")`
`replaceAll(a, b)`	replaces every a with b	`"1-2-3".replaceAll("-", "/")`
`padStart(n, c)`	pads to length n	`"7".padStart(2, "0")` → `"07"`

JavaScript

const email = "  Ahmed@SeaCode.tech "
const clean = email.trim().toLowerCase()
console.log(clean)
console.log(clean.includes("@"))
console.log(clean.split("@"))
console.log(clean.slice(0, clean.indexOf("@")))

const time = "9:5"
const [h, m] = time.split(":")
console.log(`${h.padStart(2, "0")}:${m.padStart(2, "0")}`)

You can chain methods: trim().toLowerCase().

What's the output?

console.log("JavaScript".slice(0, 4))

What will this code print?

Complete the code

Split the text at every comma.

const tags = "html,css,js"
console.log(tags.(","))

Spot the bug

This code checks the email has an @. Where's the mistake?

Exercise

Reverse "seacode" and print it (edocaes).

Expected output: edocaes

JavaScript

const word = "seacode"

Learn more from

Played 0 of 4 games