Javascript: How to check if string contain a substring

There are different ways of testing if string contains a substring., let’s take a look at few examples.

Most common and simple method would be following example, this was introduced in ES6/ES2015 and supported in most modern browsers expect IE 6 to 11.

Example1:

'Hello from the other world'.includes('other') //true

Example2:
In this example we can see the use of optional second parameter includes accepts.

'Hello from the other world'.includes('other', 2) //false
'Hello from the other world'.includes('other', 4) //true

Before ES6 indexOf() was used instead of includes()
indexOf() was the common method before ES6, that return -1 if string doesn’t contain the substring.

And it returns the index of the substring when it is found, let’s look at examples:

'Hello from the other world'.indexOf('from') !== -1 //true
'Hello from the other world'.indexOf('from', 3) !== -1 //false
'Hello from the other world'.indexOf('from', 2) !== -1 //true

That was quite simple, isn’t it.
See you in next post 🙂

About the author

Danyal Ali Butt

I'm working as programmer since 2002. Born, grew up, studied and worked in Pakistan now Im located in Denmark since 2006.

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