Validate a URL field

This set of code will validate the multi line text field and checks whether the URL entered  is valid or not. If not valid, disable the "Submit" button.

$(document).ready(function () {

    validateURL();

});

// This method is used to validate the url. If url is not valid, disable the submit button.

function validateURL() {

    $("#txtURLField").change(function () {

        if (checkUrl($("#txtURLField").val())) {

            $("#btn-id-submit").prop('disabled', false);

        }

        else {

            $("#btn-id-submit").prop('disabled', 'disabled');

            alert("Please enter a valid URL");

        }

    });

}

// This method has the URL validation properties.

function checkUrl(url) {

    //regular expression for URL

    var pattern = /^(http|https)?:\/\/[a-zA-Z0-9-\.]+\.[a-z]{2,4}/;

    if (pattern.test(url) || (url == "")) {

        return true;

    } else {

        return false;

    }

}

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