CODEWITHSUNDEEP
javascriptregex
Saurabh Gujarani
Saurabh Gujarani

Reputation: 511

RegExp word should not start with particular character for other word only find double quote word

I need to write regExp for word should not start with and only select double quotes value output

e.g

  1. notstart testing "testing" => no match

  2. start testing "testing" => "testing"

  3. anything testing testing => no match

    I have written following regExp but it does not work with second scenario

    ^(?!notstart).*(?:\s+)".*"$

Upvotes: 2

Views: 58

Answers (2)

ggorlen
ggorlen

Reputation: 56955

(?:\s+) can be reduced to \s+. /^(?!notstart).*".*"/ seems sufficient though. Ensure notstart is not at the beginning, then validate that there are at least two quotes elsewhere in the string.

[
  'notstart testing "testing"', // false
  'start testing "testing"',    // true
  'anything testing testing'    // false
].forEach(e => console.log(/^(?!notstart).*".*"/.test(e)));

If you want to capture the item in quotes:

[
  'notstart testing "testing"', // null
  'start testing "testing"',    // "testing"
  'anything testing testing'    // null
].forEach(e => console.log(e.match(/^(?!notstart).*"([^"]*)"/)));

If you want spaces around the quoted word, you can use:

const pattern = /^(?!notstart).*(?:\s|^)"([^"]*)"(?:\s|$)/;
[
  'notstart testing "testing"', // null
  'start testing "testing"',    // "testing"
  'anything testing testing',   // null
  'anything testing"testing"',  // null
  '"foo"'                       // foo
].forEach(e => console.log(e.match(pattern)));

If you want to capture all quoted strings, this should avoid backtracking:

[
  'notstart testing "testing"', // null
  'start testing "testing"',    // "testing"
  'start testing "foo" "bar"',  // "foo" "bar"
].forEach(e => {
  let m;
  
  if (!e.startsWith("notstart") && 
      (m = [...e.matchAll(/"([^"]*)"/g)]).length) {
    console.log(m);
  }
  else {
    console.log(null);
  }
});

Upvotes: 1

anubhava
anubhava

Reputation: 785156

Modern Javascript browsers support dynamic length lookbehind assertions. Hence you may consider this regex:

/(?<!^notstart.*?)"[^"]*"/gmi

RegEx Demo

  • (?<!^notstart.*?): Negative lookbehind assertion to fail the match if a match has notstart at line start.
  • "[^"]*": Match a quoted word. (This doesn't take care of escaped or unbalanced quotes).

Upvotes: 3

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