CODEWITHSUNDEEP
javascriptregexglobal
StefanHayden
StefanHayden

Reputation: 3669

Javascript Regexp not returning global results

It's my understanding that all three of these lines below should return an ARRAY with 2 results in it. Yet RegExp will only return 1 result no matter how many times the regex repeats in the string.

Can some one explain why? And perhaps suggest how I can get RegExp to give me global results?

//INTPUT: 
    console.log(new RegExp("New York", "gi").exec("New York New York")); 

//OUTPUT: 
["New York"]

//INTPUT: 
    console.log(new RegExp(/New York/gi).exec("New York New York"));

//OUTPUT: 
["New York"]

//INTPUT: 
    console.log("New York New York".match(/New York/gi));

//OUTPUT:
["New York", "New York"]

Upvotes: 17

Views: 10155

Answers (2)

Derek Swingley
Derek Swingley

Reputation: 8752

This is expected, exec() returns a single match but provides more info about the match than match(). If you just want all the matches, use match(). From JavaScript: The Definitive Guide:

Recall that match() returns an array of matches when passed a global regular expresion. exec(), by contrast, always returns a single match and provides complete information about that match. When exec() is called on a regular epression that has the g flag, it sets the lastIndex property of the matched substring. When exec() is invoked a second time for the same regular expression, it begins its search at the character position indicated by the lastIndex property.

Upvotes: 13

Rob Fonseca-Ensor
Rob Fonseca-Ensor

Reputation: 15621

your third example is the best way to get the array of matches.

RegExp.exec actually remembers its position, and returns the next result on subsequent calls:

>>> var v = /new york/gi
>>> v.exec("NEW YORK new york")
["NEW YORK"]
>>> v.exec("NEW YORK new york")
["new york"]
>>> v.exec("NEW YORK new york")
null

Upvotes: 26

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