Javascript - Regular expression for extract numbers from the string

SarjeraoGhadage
May 22, 2023
190 views
0 votes
2 Answers

I need to extract numbers from the string for that I have preferred the following regix

var str = "1 1/2 percentage";
var n = str.match(/[0-9]+([/.]d+)?/g);
console.log(n);

But I am not able to restrict negative numbers in the string .

Valid Scenario:

"1.5 % dividend applied"
"1 1/2 percentage"
 "1/10 percentage"
"2.5 percentages"
"10% dividend"
"10 percentages applied"

Invalid Scenario:

"-1 1/2 percentage"
"-1.5 % dividend applied"
"-10% dividend"

Code suggestion will be appriciated.Thank you

Tags: javascript regex

Answers

With a mix of javascript and regex:

function getNumbers(text) {
    //match all numbers
    var matches = text.match(/-?d+([/.]d+)?/g);
    var res = [];

    for (var i = 0; i < matches.length; i++) {
        var match = matches[i];

        if (!match.startsWith('-')) { // check if its not a negative number
            result.push(match);
        }
    }

    return res;
}

You need:

/(?<![-.d])d+([/.]d+)?/g

Explanation:

(?<![-.d])   # Match something that is not preceded by '-', '.' or a digit,
d+           # starts with 1+ digits, and
([/.]d+)?   # ends with either a '/' or a '.' followed by 1+ digits

Try it on regex101.com.

Try it:

console.config({ maximize: true });

const testcases = [
  '1.5 % dividend applied',
  '1 1/2 percentage',
  '1/10 percentages',
  '2.5 percentages',
  '10% dividend',
  '18.6 foo',
  '10 percentages applied',
  '-1 1/2 percentage',
  '-1.5 % dividend applied',
  '-10% dividend',
  '-18.6 foo'
];

const regex = /(?<![-.d])d+([/.]d+)?/g;

for (const testcase of testcases) {
  console.log(`'${testcase}'`, testcase.match(regex) ?? 'no match');
}

<script src="https://gh-canon.github.io/stack-snippet-console/console.min.js"></script>

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Javascript – Regular expression for extract numbers from the string

Answers