jQuery Add http:// as prefix to text input if there is none

问题

I have a text input that need an url as value (complete of http://) and I want that if the user don't writes it himself if gets added automatically. My code as follows,

jQuery

$('.txtUrl').keypress(function(e) {
    if(e.keyCode == 13) {
        var ini = $(this).val().substring(0,3);
        if (ini === 'http'){
            $.noop()
        }
        else {
            // get value from field
            var cur_val = $(this).val(); 
            // do with cur_val
            $(this).val('http://' + cur_val);
        }        
    }
});

HTML

<input type="text" class="txtUrl" />

Problem in Fiddle

回答1:

You're comparing http to the three first characters (substring(0,3)) of the text which, of course, never will be true. Change it to:

var ini = $(this).val().substring(0, 4);

回答2:

http://jsfiddle.net/bitsmix/jMH9b/

if ($(this).val().match(/^http/))

regex always better :)

来源：https://stackoverflow.com/questions/7817636/jquery-add-http-as-prefix-to-text-input-if-there-is-none