regex test V S string match to know if a string matches a regular expression

Question

Many times I m using the string match function to know if a string matches a regular expression     if str match   regex       Is there any difference between this   if    regex   test str     They seem to give the same result

User · Answer

This is my benchmark results   test  4 267 740 ops sec   1 32   60 runs sampled  exec  3 649 719 ops sec   2 51   60 runs sampled  match 3 623 125 ops sec   1 85   62 runs sampled  indexOf 6 230 325 ops sec   0 95   62 runs sampled   test method is faster than the match method  but the fastest method is the indexOf

User · Answer

Don t forget to take into consideration the global flag in your regexp    var reg    abc g     abcdefghi  match reg        gt  true    abcdefghi  match reg        gt  true reg test  abcdefghi            gt  true reg test  abcdefghi            gt  false  lt     This is because Regexp keeps track of the lastIndex when a new match is found

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Basic Usage  First  let s see what each function does   regexObject test  String       Executes the search for a match between a regular expression and a specified string  Returns true or false    string match  RegExp       Used to retrieve the matches when matching a string against a regular expression  Returns an array with the matches or null if there are none    Since null evaluates to false   if   string match regex           There was a match    else        No match         Performance  Is there any difference regarding performance    Yes  I found this short note in the MDN site      If you need to know if a string matches a regular expression regexp  use regexp test string     Is the difference significant    The answer once more is YES  This jsPerf I put together shows the difference is   30  -  60  depending on the browser     Conclusion  Use  test if you want a faster boolean check  Use  match to retrieve all matches when using the g global flag

[javascript] regex.test V.S. string.match to know if a string matches a regular expression

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