CODEWITHSUNDEEP
javascriptregexstring
vijar
vijar

Reputation: 781

How to get substring using regex

I am trying to get a couple values out of a url using regular expression. Since i am not familiar i was hoping someone could guide me .

I have a url i am trying to manipulate looks like this . 

var urlString = "/myMessages/v2/messages/I15/parts/0"

The values i am trying to get are I15 and 0 . These values could be anything but the format of urlString would remain the same. What is the best and most efficient way to go about obtaining these values?

Upvotes: 0

Views: 108

Answers (6)

Brian Stephens
Brian Stephens

Reputation: 5271

\/messages\/([^\/]+)\/parts\/(.*)

Then use the first and second matched groups.

Upvotes: 0

RevanProdigalKnight
RevanProdigalKnight

Reputation: 1326

I'd suggest a slightly more robust solution than what's been proposed so far:

var urlString = "<url string coming in some undetermined order>";
var parts = urlString.split('/');
var map = {};
for (var i = 0; i < parts.length; i += 2) {
  map[parts[i]] = parts[i+1];
}

This way your values are now stored along with the keys to access them, which you can set in any way you want.

So say your URL is /myMessages/v2/partnum/2/messages/I18/thing/splund/foo/bar and you want the values of partnum, thing, and foo, but you don't necessarily know that they'll be in the order I just put up in that url. Using the method I suggested, you can simply access their values using:

var partnum = map['partnum'] // '2'
var thing = map['thing']     // 'splund'
var foo = map['foo']         // 'bar'

Upvotes: 2

Matthew Graves
Matthew Graves

Reputation: 3294

I'm not sure I would use regex for this. I would create a custom function to handle urls of this type:

function handleUrlTokens(url){
  var parts = url.split('/').filter(function(o){return o!==''})
  var params = {};
  for (var i = 0; i < parts.length; i+=2) {
    param[parts[i]] = parts[i+1];
  }
  return params;
}
handleUrlTokens("/myMessages/v2/messages/I15/parts/0") //Object {myMessages: "v2", messages: "I15", parts: "0"}

This would then be able to handle many different types of url, as long as the convention is /key/value/key/value.

Edited because revenProdigalKnight's loop was better than mine.

Upvotes: 2

p.s.w.g
p.s.w.g

Reputation: 149058

For something this simple, a straightforward solution is to use split instead:

var urlString = "/myMessages/v2/messages/I15/parts/0";
var parts = urlString.split('/');
var value1 = parts[4]; // "I15"
var value2 = parts[6]; // "0"

This will work just fine as long as you know exactly how many / characters will appear before the parts you're interested in.

If you also know that the URL will always begin with "/myMessages/v2/messages/", you might be able to make this a bit more efficient:

var urlString = "/myMessages/v2/messages/I15/parts/0";
var substring = urlString.substr(24), 
    i = substring.indexOf('/'),
    j = substring.indexOf('/', i);
var value1 = substring.substr(0, i);  // "I15"
var value2 = substring.substr(j + 1); // "0"

However, efficiency really shouldn't be your first priority. You should optimize for readability.

Upvotes: 1

Raja Sekar
Raja Sekar

Reputation: 2130

var urlString = "/myMessages/v2/messages/I15/parts/0"
var reqArray = urlString.split('/');

console.log(reqArray[4],reqArray[6]);

This is the better way, when compared to regular expression.

It works fine for me!!

Upvotes: 0

Fueled By Coffee
Fueled By Coffee

Reputation: 2569

var first = urlString.split('/')[4];
var second = urlString.split('/')[6];

Note that this will not work if the order is changed.

Upvotes: 0

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