How to validate youtube url in client side in text box

Escape all the forward slashes present in your regex and then put the modified regex within / delimiter without any spaces or comment lines and you don't need to add x modifier.

var re = /^(?:https?:\/\/)?(?:www\.)?(?:youtube\.com|youtu\.be)\/watch\?v=([^&]+)/m;

Combining the answers from here, and some modification, I came up with this regexp:

^(?:https?:\/\/)?(?:m\.|www\.)?(?:youtu\.be\/|youtube\.com\/(?:embed\/|v\/|watch\?v=|watch\?.+&v=))((\w|-){11})(\?\S*)?$

This will match any format, but will mismatch if the id is longer than 11 characters. Also able to add start video tag with the "?" part at the end.

You can test it by pasting it into this

Here is the code which validates the youtube url-

function validateYouTubeUrl()
{
    var url = $('#youTubeUrl').val();
        if (url != undefined || url != '') {
            var regExp = /^.*(youtu.be\/|v\/|u\/\w\/|embed\/|watch\?v=|\&v=|\?v=)([^#\&\?]*).*/;
            var match = url.match(regExp);
            if (match && match[2].length == 11) {
                // Do anything for being valid
                // if need to change the url to embed url then use below line
                $('#ytplayerSide').attr('src', 'https://www.youtube.com/embed/' + match[2] + '?autoplay=0');
            }
            else {
                // Do anything for not being valid
            }
        }
}

Fiddle Url: https://jsfiddle.net/cpjushnn/12/

See this working example:

function matchYoutubeUrl(url) {
    var p = /^(?:https?:\/\/)?(?:m\.|www\.)?(?:youtu\.be\/|youtube\.com\/(?:embed\/|v\/|watch\?v=|watch\?.+&v=))((\w|-){11})(?:\S+)?$/;
    if(url.match(p)){
        return url.match(p)[1];
    }
    return false;
}

Updated Fiddle: http://jsfiddle.net/3ouq9u3v/13/