Javascript/JQuery : How do I count the words separated with a comma?

Question

Javascript:

$(document).ready(function()
{
    $('#field').keyup(function()
    {
        var count = '??';

        $('#count').html(count);
    });
});

HTML:

<input type="text" id="field" /> <span id="count">5</span>

示例(单词总是用逗号分隔):

example 1: word, word word
count: (5 - 2) = 3

example 2: word
count: (5 - 1) = 4

example 3: word, word,
count: (5 - 2) = 3

example 4: word, word, word
count: (5 - 3) = 2

因此，我需要计算有多少个单词以逗号分隔，但例如示例 3 中所示，不应将它们计为3 个单词仅当逗号后也有单词时。

并且不应允许用户输入超过 5 个单词。

Answer 1

类似于:

$("#input").keyup(function(){
    var value = $(this).val().replace(" ", "");
    var words = value.split(",");

    if(words.length > 5){
        alert("Hey! That's more than 5 words!");
        $(this).val("");
    }
});

jsFiddle 示例:http://jsfiddle.net/BzN5W/

编辑:

更好的例子:http://jsfiddle.net/BzN5W/2/

$("#input").keypress(function(e){
    var value = $(this).val().replace(" ", "");
    var words = value.split(",");

    if(words.length > 5){
        //alert("Hey! That's more than 5 words!");
        e.preventDefault();
    }
});