Question

function getCode() {
    if (window.location.href.indexOf("?discount=")) {
        var url = (document.URL);
        var id = url.substring(url.lastIndexOf('=') + 1);
        window.alert(id);
        return true;
    } else {
        return false;
    }
}

Purpose: When people go to our “Service Request” page using a QR code that has a substring of ?discount=1234. I have been testing by creating an alert box with the discount code showing. Eventually I want to be able to populate that “1234” automatically into a “Discount Code:” text field on page load.

The above is a mixture of a few suggestions when I researched it.

Result: Going to example.com/serviceRequest.html?discount=1234 gives me the appropriate alert “1234”, as I want… Going to example.com/serviceRequest.html gives me the alert http://example.com/serviceRequest.html, but I don’t want anything to happen if “?discount=” is null.

Any suggestions?

Answer 1

indexOf returns -1 if the search pattern doesn’t exist. In JavaScript, anything not a 0 or false or undefined is considered true.

So your line of:

if(window.location.href.indexOf("?discount=")) {

Would better search as:

if(window.location.href.indexOf("?discount=") > -1) {