JAVASCRIPT

Replacing and Spliting JavaScript Sub Strings

In this second part of a two-part series on JavaScript String regular expressions, I look at multiline matching, how to replace matched sub-strings and how to split an available string using a regular expression object. Before we do that, let us look at the String way of extracting matches and then compare it with that of the RegExp object.

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By: Chrysanthus Forcha

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October 01, 2009

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Note: The JavaScript String object has the match() method; it is not the RegExp object that has the method. This method returns an array of one element (the first) if it sees a match. If you use a global flag, then the elements in the array will be all the sub-strings found. The way the String match() method is used is straightforward. There is no ambiguity, as we shall see below.

Consider the regexp,

re = /rat/;

Consider the available string,

"A cat is an animal. A rat is an animal. A bat is an animal."

The pattern should match "rat" in the available string. The alert statement in the following code displays a one-element array, with one value, "rat."

<html>

<head>

</head>

<body>

var availableString = "A cat is an animal. A rat is an animal. A bat is an animal.";

var re = /cat/;

myArray = availableString.match(re);

alert(myArray);

</script>

</body>

</html>

We have used the string match method in the statement:

myArray = availableString.match(re);

Only one match could occur in the available string; only one element was matched, therefore the returned array has only one element, "rat" as expected. If no matching occurs, null is returned; an array is not returned; the same is true with the exec() method.

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