- Because JavaScript uses the same data type (string) for multi-letter text and single characters, you can use the same approach to count the number of times either appears in another string.
- We'll use the split() method, which takes a character or string, and uses it to separate another string into array elements - we'll have one more array element than the number of matches found:
var str = "The foxy fox jumps before dancing the Foxtrot.";
// Make search case-insensitive by converting to lower:
var foxSplit = str.toLowerCase().split("fox");
var foxCount = foxSplit.length - 1;
alert( "Found " + foxCount + " matches for 'fox' in the string" );Note: by using toLowerCase(), we ensure that the last instance (capitalized) will be counted! You can also pass escaped characters as argument, like "\n" for new lines or "\t" for tabs.
- You can use regular expressions to search text more flexibly. The code below counts all the words that start with "fox", but also includes letters after that - expected matches are highlighted:
var str = "The foxy fox jumps before dancing the Foxtrot.";
// "g" option to count all; "i" option to make case-insensitive
var rgx = /\sfox\S+/gi;
alert( "Found " + str.match(rgx).length + " matches!" );Tip: the match() method captures each matching string, and returns them as an array of strings.
- To quickly check if a string contains another before doing any work, consider using indexOf().
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