Javascript check undefined

Check if there is a empty value of some sort or empty string/array/etc.

by Plippie Plop

HTML

<div id="a">string: a="" (typeof a=="undefined")</div>
<div id="b">String: b=null (typeof b=="undefined")</div>
<div id="c">Array: c=[] (typeof c[0]=="undefined")</div>
<div id="d">Object: d={} (typeof d[0]=="undefined")</div>
<div id="e">var e= (typeof e=="undefined")</div>
<div id="f">var f=0 (typeof f=="undefined")</div>
<div id="g">var g="" (g =="" || typeof g =="undefined" || g==null) </div>
<div id="h">var h={a:""} (typeof h="undefined")</div>
<div id="i">var h={a:""} (typeof h[0]="undefined")</div>
<div id="j">var gem="" ( gem !== "")</div>
<div><span class="yes">Green=Defined</span><br><span class="no">Red=Undefined</span></div>

CSS

div{
    border:1px solid black;
    padding:5px;
    margin:5px;
    width:auto;
    font-family:verdana;
    display:block;
}
.no{border:1px solid red;color:red;margin:2px;}
.yes{border:1px solid green;color:green;margin:2px;}

JavaScript

var a = "",
    b = null,
    c = [],
    d = {},
    e, f = 0,
    g = "",
    h={a:""},
    gem="";




    if (typeof a == "undefined") {
        $("#a").addClass("no");
    } else {
        $("#a").addClass("yes");
    }

    if (typeof b == "undefined") {
        $("#b").addClass("no");
    } else {
        $("#b").addClass("yes");
    }

    if (typeof c[0] == "undefined") {
        $("#c").addClass("no");
    } else {
        $("#c").addClass("yes");
    }

    if (typeof d[0] == "undefined") {
        $("#d").addClass("no");
    } else {
        $("#d").addClass("yes");
    }

    if (typeof e == "undefined") {
        $("#e").addClass("no");
    } else {
        $("#e").addClass("yes");
    }

    if (typeof f == "undefined") {
        $("#f").addClass("no");
    } else {
        $("#f").addClass("yes");
    }

    if (g == "" || typeof g == "undefined" || g == null) {
        $("#g").addClass("no");
    } else {
        $("#g").addClass("yes");
    }

    if (typeof h == "undefined") {
        $("#h").addClass("no");
    } else {
        $("#h").addClass("yes");
    }

    if (typeof h[0] == "undefined") {
        $("#i").addClass("no");
    } else {
        $("#i").addClass("yes");
    }

if ( gem !== ""){
      $("#j").addClass("yes");
    } else {
        $("#j").addClass("no");
    }