I'm trying to return the number of times a letter appears in a word.
I'm passing the letter to a function like so
function getCount(letter)
{
var pattern = '/' + letter + '/g';
var matches = word.match(pattern);
return matches.length;
}
Unfortunately matches is null so I'm unable to call length on it, I know the letter appears in the word as I've already checked that
word.indexOf(letter) > -1
I suspect the problem is with the way I'm building or evaluating pattern
Here's how you build a non literal regular expression :
var pattern = new RegExp(letter, 'g');
See the MDN on building a regular expression.
And here's a simpler solution to count the occurrences of the letter :
return word.split(letter).length-1;
word.split(letter).length-1.'ergo'.split('e').length - 1; // 1. It's a neat solution anyhow.You can do this:
function hasClass(letter) {
var pattern = new RegExp(letter,'g'); // Create a regular expression from the string
var matches = word.match(pattern);
return matches;
Ref: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/RegExp
This was also answered here: javascript new regexp from string
