Javascript Regular Expression: Greedy Matching

One particularly challenging aspect facing those new to regular expressions is

greedy matching. Often termed aggressive or maximal matching.A simple way to

think about this is that JavaScript will continue matching characters if at

all possible.

Here is example

Code:

var pattern =/(ma.*ing)/

var sentence = "Regular Expression matching can be daunting task"

pattern.test(sentence)

console.log(RegExp.$1)

Output:

matching can be daunting

Explanation:

you might think that the pattern would match the word “matching”.

but the actual output is shown in the following illustration.

JavaScript matchesthe longest substring it can, in this case

from the initial “ma” in matching all the way to the final

“ing” in “daunting.”