Question

I have created a JavaScript function for validation of US Driving License. Issue is function is browser dependent. That is function creates error in IE but run fine in MOZILLA AND CHROME..

I have validated it as first three digit should be either 0 or 1 or 2 or 3.

    //license number
    var strFilter = /^[0-9]*$/;
    var chkVal36 = document.getElementById("license").value;
    var chkVal37 = document.getElementById("license").value.length;
    var chkVal38 = document.getElementById("license").value;

    if ((!strFilter.test(chkVal36)) || ((chkVal36 !== "") && (chkVal36 === 0)) || (chkVal36 !== "") || (chkVal37 !== 8) || ((chkVal38[0] !== 0) && (chkVal38[0] !== 1) && (chkVal38[0] !== 2) && (chkVal38[0] !== 3))) {
        alert("Please enter valid 8-digit license number\r\n(Only digits)");
        document.getElementById("license").focus();
        document.getElementById("license").style.background = "#DFE32D";
        document.getElementById("license").value = null;
        return false;
    }

Answer 1

You can’t do string array indexing like chkVal38[0] in older versions of IE.

I would suggest this cleaned up and simplified code:

//license number
var strFilter = /^[0-3][0-9]{7}$/;
var obj = document.getElementById("license");

if (!strFilter.test(obj.value)) {
    alert("Please enter valid 8-digit license number\r\n(Only digits)");
    obj.focus();
    obj.style.background = "#DFE32D";
    obj.value = "";
    return false;
}

Working example here: http://jsfiddle.net/jfriend00/ZUajd/

Changes:

• Moved all the validation into the single regex (leading 0-3, all numbers and 8 total chars).
• Retrieved the DOM object once and then use that reference rather than retrieving it every time
• Clear the field by setting to “”, not null.