05_additional_string_methods.md

Chapter 5: Additional string methods

Additional string methods

We are going to cover 4 new strings method:

• startsWith()
• endsWith()
• includes()
• repeat()

 

startsWith()

This new method will check if the string starts with the value we pass in:

const code = "ABCDEFG";

code.startsWith("ABB");
// false
code.startsWith("abc");
// false, startsWith is case sensitive
code.startsWith("ABC");
// true

We can pass an additional parameter, which is the starting point where the method will begin checking.

const code = "ABCDEFGHI"

code.startsWith("DEF",3);
// true, it will begin checking after 3 characters

 

endsWith()

Similarly to startsWith() this new method will check if the string ends with the value we pass in:

const code = "ABCDEF";

code.endsWith("DDD");
// false
code.endsWith("def");
// false, endsWith is case sensitive
code.endsWith("DEF");
// true

We can pass an additional parameter, which is the number of digits we want to consider when checking the ending.

const code = "ABCDEFGHI"

code.endsWith("EF", 6);
// true, 6 means that we consider only the first 6 values ABCDEF, and yes this string ends with EF therefore we get *true*

 

includes()

This method will check if our string includes the value we pass in.

const code = "ABCDEF"

code.includes("ABB");
// false
code.includes("abc");
// false, includes is case sensitive
code.includes("CDE");
// true

 

repeat()

As the name suggests, this new method will repeat what we pass in.

let hello = "Hi";
console.log(hello.repeat(10));
// "HiHiHiHiHiHiHiHiHiHi"