I need to count occurrences of an array in a string. I have problems with the special characters like ;/()
var msg = "hello world :)";
var tce = [":)", ":(", ":/" ];
var countOcurrences = 0;
for (var i = 0; i < tce.length; i++) {
res = msg.match(/tce[i]/g);
if (res != null) countOcurrences += res.length;
}
I think with regular expression, it may become more easy.
Forget about using regex and just use a simple indexOf to check for number of occurances. This function will help you:
function countMatches(str, find) {
var count = 0;
var index = str.indexOf(find);
while (index != -1) {
count++;
index = str.indexOf(find, index + 1);
}
return count;
}
which you can use like this:
var msg = "hello world :)";
var tce = [":)", ":(", ":/"];
var countOcurrences = 0;
for (var i = 0; i < tce.length; i++) {
countOcurrences += countMatches(msg, tce[i]);
}
In fact, you don't need any loops at all. Just construct one big regexp with alternatives (|) and match the string against it:
var tce = [":)", ":(", ":/"];
// http://stackoverflow.com/a/3561711/989121
RegExp.escape= function(s) {
return s.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')
}
var re = RegExp(tce.map(RegExp.escape).join('|'), "g");
var msg = "hello :/ world :):)";
var countOcurrences = (msg.match(re) || "").length; // 3
Change the array values to this:
var tce = [":\)", ":\(", ":/" ];
You need to escape ( and ) while using regex.
Don't use a regular expression for exact string matches.
You can use indexOf, use the 2nd parameter offset to find and count all occurrences.
var pos = msg.indexOf(str);
if (pos === -1) {
// no match
}
var last_pos = pos;
pos = msg.indexOf(str, last_pos + 1);
if (pos !== -1) {
counter += 1;
}
Do that in a loop, basically ^
last_pos needs to be incremented before before used in the subsequent indexOf calls, otherwise it will endlessly match the same index