How to correctly check if a string match regex in javascript

I want to check if a string match the following pattern

Having a text contains between Two "and each text can be separated to another by a ; the appending ;is mantatory

I tried with the regular expression /"(.*?)";?/ but can’t make it work

In the code snippet below test3 return true but should not match the regex

I don’t know if it’s my regex or the way I try my regex

const regex = /"(.*?)";?/;

const test = `"hello"; "world";`;
const test2 = `"hello"; "world"`;

const test3 = `"hello; "world"`;
const test4 = `"hello"; world`;
const test5 = `"hello""world"`;

//should be true

//should be false

>Solution :


… can be broken down into …

  1. /^ ... $/
  2. "[^"]*"
  3. (?:\s*;\s*"[^"]*")+
  4. ;?

… which then translates to …

  1. In between new line start and line end …
  2. match a double quote, followed by an optional sequence of characters, each character not being a double quote, followed by a double quote.
  3. group ( ... ) the following match but do not capture it (?: ... ) and force this pattern to be present at least once (?: ... )+ … within this group …
    • match the sequence of an optional whitespace (WS) a semicolon and another optional WS followed by the pattern already described with/under (2).
  4. the entire match is allowed to end with none or exactly one semicolon.
const regex = /^"[^"]*"(?:\s*;\s*"[^"]*")+;?$/;

const test1 = `"hello"; "world";`;
const test1a = `"hello" ; "world" ;"world"; "world"`;
const test2 = `"hello" ; "world"`;
const test2a = `"hello";"world" ; "world";"world"`;

const test3 = `"hello; "world"`;
const test4 = `"hello"; world`;
const test5 = `"hello""world"`;

const test6 = `"hello ; world;";"hello ;world"`;

const test6a = `"hello ;world;" "hello; world"`;
const test6b = `"hello; world"`;

//should be true
console.log("test1", regex.test(test1));
console.log("test1a", regex.test(test1a));
console.log("test2", regex.test(test2));
console.log("test2a", regex.test(test2a));

console.log("test6", regex.test(test6));

//should be false
console.log("test3", regex.test(test3));
console.log("test4", regex.test(test4));
console.log("test5", regex.test(test5));

console.log("test6a", regex.test(test6a));
console.log("test6b", regex.test(test6b));
.as-console-wrapper { min-height: 100%!important; top: 0; }

Leave a Reply