Question

i work in javascript and like to check if my text has some signs. I’d like to check if my text has ( ) and & letters or it has repeating letters in it. Some examples:

test – has multiple t

tes&t – has &

test(test) – has ( and ), multiple t and twice ‘e’ letter

test&(test – has & and ( and multiple t and e

test&(&t – has multiple t, multiple & and (

tesra – this one doesnt fits any patterns

I’ve already made something like this:

if ((/(\w+)(?=\1)/g).test(str)) alert('multiple signs')

but it only counts multiple signs if they are one after another so ‘teest’ would fit pattern and test wouldnt. Can anybody help me? I never could understand all those regexp features 🙁
It can be divided in two regexp.

Thanx in advance

Answer 1

This should do it, though it might not be very efficient (since it is not anchored):

(?:[&()]|(\w)[^\1]*\1)

An alternative would be to simply iterate over the characters, inspect and count them:

function contains_multiple_chars(str, extra) {
    var chars = {};
    for(var i = 0,l = str.length; i < l;i++) {
        var c = str.charAt(i);
        if(c in chars || c in extra) {
            return true;
        }
        else {
            chars[c] = 1;
        }
    }
    return false;
}

var multiple = contains_multiple_chars(str, {'(': 1, ')': 1, '&': 1});

(I admit the function name does not fit very well)