How to extract a substring from a string in JavaScript?

Question

I have a string of the following format:

var str1="tag:youtube.com,2008:video:VrtMalb-XcQ";

From this I need to extract the last part i.e. VrtMalb-XcQ. How can I achieve this?

Take a look here: use the lastIndexOf on 'x' and use the substring method. w3schools.com/jsref/jsref_obj_string.asp — Stultuske
– Stultuske, Commented Jan 27, 2015 at 14:13

Simon Forsberg · Accepted Answer · 2015-01-27 14:14:39Z

5

What you need to know is the index of the last :. This can be achieved by using lastIndexOf

var str1="tag:youtube.com,2008:video:VrtMalb-XcQ";
var result = str1.substr(str1.lastIndexOf(':') + 1);

The + 1 is there because otherwise you would also get the colon itself in the string.

This is really the fastest approach to do it, and requires the least memory.

answered Jan 27, 2015 at 14:14

Simon Forsberg

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Comments

Kirill Pisarev · Accepted Answer · 2015-01-27 14:11:53Z

2

use split and pop:

var str1="tag:youtube.com,2008:video:VrtMalb-XcQ";
str1.split(':').pop()

answered Jan 27, 2015 at 14:11

Kirill Pisarev

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4 Comments

Simon Forsberg Over a year ago

It is totally unnecessary to split the whole thing when all you need is the index of the last ':'

Kirill Pisarev Over a year ago

@SimonAndréForsberg ... why it's unnecessary?? it's just the simple and short solution, thats works great

Simon Forsberg Over a year ago

It is a waste of CPU power and memory. It is doing more job than is really required (small waste, but still a waste)

Simon Forsberg Over a year ago

As I said: It is a small waste, but still a waste. It definitely gets the job done, but it's not the most optimal way.

zzzhc · Accepted Answer · 2015-01-27 14:14:50Z

0

 "tag:youtube.com,2008:video:VrtMalb-XcQ".replace(/.*:/, "")

answered Jan 27, 2015 at 14:14

zzzhc

3951 silver badge7 bronze badges

4 Comments

Simon Forsberg Over a year ago

Using regex for this? Seriously? I don't think this is a good solution

Ruan Mendes Over a year ago

@SimonAndréForsberg Not worth a downvote, it does work

Simon Forsberg Over a year ago

@JuanMendes Sorry, I'm way too active on Code Review to do anything else. Additionally, there is no description at all, just a code dump.

zzzhc Over a year ago

why not regex? it's clean and simple.

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