Using Regular Expressions to Extract Values in Javascript

Question

I have a string in the form: "xMyS"

I want to extract x and y in using the Javascript Regex expressions.

For example, if the string is

10M225S

I need 10 and 225 from this.

Also, the string might not have either of x or y part. For example it can be just 225S or just 10M.

EDIT: I tried things like .match(), but don't know how to extract values in the mentioned format.

EDIT: The regex I tried so far is /(\w+)M(\w+)S/, but it seems to only work for 10M225S and not for 10M and 225S.

What have you tried so far? Did you google "javascript regular expressions"? — slim
– slim, Commented Dec 14, 2016 at 14:17
Yes...I did google about it. Found about .match(), but can't seem to get it done. — dsaket
– dsaket, Commented Dec 14, 2016 at 14:18

Terminater · Accepted Answer · 2016-12-14 14:57:16Z

15

You can do something like this:

var str = "10M255S"
var match = str.match(/^([0-9]*)M*([0-9]*)S*$/)

Then match[1] is 10 and match[2] is 255

If var str = "10M", then match[1] is 10 and if var str = "255S", then match[1] is 255

In any of the three cases, matches start from second element of the array match.

Hope this helps.

answered Dec 14, 2016 at 14:57

Terminater

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4 Comments

dsaket Over a year ago

But it gives same result for 10M and 10S. How would I distinguish?

Terminater Over a year ago

True, it does. As per the question, you said you want to extract the x and/or y's which are related to M and S respectively. If you supply same x and y values in the string, why do you want to distinguish between them (as both are same)?

Terminater Over a year ago

And if you really want to distinguish between tose two, use the first element in match array, which gives the whole matched string.

dsaket Over a year ago

Thank you so much for the help!!

iHasCodeForU · Accepted Answer · 2016-12-14 14:28:56Z

2

you can use .split() to split the strings:

var str = "10M225S"
var m = str.split("M")[0];
var s = str.split("M")[1].split("S")[0];

console.log("m >>> " + m);
console.log("s >>> " + s);

no need for regular expressions in this case.

answered Dec 14, 2016 at 14:28

iHasCodeForU

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3 Comments

dsaket Over a year ago

Thanks for the alternative. But I need a regex approach.

slim Over a year ago

@dsaket Why? Because it's homework? If so then it's likely your tutor has given you the documentation you need.

dsaket Over a year ago

No..it's a situation I encountered when I was working on an app.

RamblinRose · Accepted Answer · 2016-12-14 15:10:59Z

0

K-Gun's answer makes sense if the pattern never varies, however if 'M' and 'S' are simply placeholder examples for arbitrary text, then use the RegExp /\d+/g

<!DOCTYPE html>
<html>
<head>
  <script>
    function fn() {
      var re = /\d+/g, // match digits, globally
        str = '10M225S',
        result = [],
        temp;
      // process successive matches
      while ((temp = re.exec(str)) !== null)
        result.push(temp[0]);

      document.getElementById("result").innerText = result.toString();
    }
  </script>
</head>
<body onload="fn()">
  <h1 id="result"></h1>
</body>
</html>

Here's a plunkr demonstrating the code.

The RegExp re will match runs of digits. This will work regardless of any non-digit characters, e.g. it would match "10ZXZZ225FOZ".

edited Dec 14, 2016 at 15:10

answered Dec 14, 2016 at 14:58

RamblinRose

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2 Comments

dsaket Over a year ago

it gives the same result for 10M and 10S. i.e. 10. How would I distinguish?

RamblinRose Over a year ago

@dsaket have a look at the plunkr I linked because that is incorrect.

Muhammad Ridwan · Accepted Answer · 2021-01-19 11:18:09Z

0

var str = "10M255S"
var result = str.match(/([0-9])/g)

var value = []
result.map(res => {
  value += res
})
console.log(value)

answered Jan 19, 2021 at 11:18

Muhammad Ridwan

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2 Comments

mousetail Over a year ago

Consider explaining your code, so OP and other future readers know what the purpose is and how it solved the problem.

Zsolt Meszaros Over a year ago

Using .map() and not using the returned value? Did you want to use forEach()? And I'm not sure if it answers the question, as your current code returns a string like 10255, not what OP wanted.

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