When Should You Use exec vs. match in JavaScript? A Clear Guide

1. Which Object Owns exec and match?

exec is a method of the RegExp class. match is a method of the String class.

Understanding the owning object makes it clear how to use each method.

Example:

/hello/.exec('hello world');

'hello world'.match(/hello/);

2. The Key Difference

In short, it’s about the g flag. exec always matches the first occurrence (the g flag does not affect it) and returns information about captured groups. match returns an array of all matches only when the regular expression includes the g flag.

When the g flag is present, match can return multiple results, while exec still returns only the first match.

Conversely, if the regular expression does not have the g flag, match behaves like exec and returns a single match.

Example code (both functions return ["version2.1","version","2","1"]):

var str = "version2.1";
var re = /([a-z]+)(\d+)\.(\d+)/;
console.log(str.match(re));
console.log(re.exec(str));

In summary, the differences are twofold: they belong to different classes, and their behavior depends on whether the regular expression uses the g flag.

Reference

http://www.cnblogs.com/xiehuiqi220/archive/2008/12/01/1327487.html