Question

I need to remove a prefix from a string. Given an array of known prefixes, I do not know which prefix will exist in a string. One and only one prefix will exist.

    function CleanupSupportedItems(data) {
        var prefixes = new Array("TrialLeads", "IPG");

        for (var i = 0; i < prefixes.length - 1; i++) {
            var prefix = new RegExp(/prefixes[i]/g);
            //alert(prefix);
            data = data.replace(prefix, "");
            alert(data);
        }
    }

The above code returns undefined on the second iteration.

Given the call

CleanupSupportedItems("TrialLeads11");

I want a return value of “11”. How can I do it?

Answer 1

You can do without the loop:

function CleanupSupportedItems(data) {
    var prefixes = new Array("TrialLeads", "IPG");

    var prefix = new RegExp('^(' + prefixes.join('|') + ')', "g");
    data = data.replace(prefix, "");
    alert(data);
}

CleanupSupportedItems("TrialLeads11");  // alerts 11
CleanupSupportedItems("IPG12");   // alerts 12

Here’s demo: http://jsfiddle.net/mrchief/KkRFp/

Updated to make sure it replaced only prefixes and not in between body. Thanks to minitech for pointing it out.

As a suggested improvement, if the input prefixes are expected to have Regex Special characters, they would need to be escaped.