Q:

Tumblr "like-heart-button" script on homepage

How to make a 'like' button for each post without going on permalink page? I mean, even in the homepage, which script can I use to have something like the heart on this page? (mouseover the photos, there's a heart to like the post)

A:

I've created a tutorial on this at: http://like-button.tumblr.com. It eliminates the problems people have with implementing this and makes it a simple cut and paste.
To add Like functionality, you use the following URL and set it as the src attribute of an invisible <iframe>:
http://www.tumblr.com/<command>/<oauthId>?id=<postId>

<command>: like or unlike
<oauthId>: last eight characters of {ReblogURL}
<postId>: {PostID}

Example:
http://www.tumblr.com/like/fGKvAJgQ?id=16664837215

Cut and paste the following code block into your theme immediately before </head>. This will give you a Like button on each post that looks like the default Tumblr grey heart. It will turn red when you hover over it and when you click it. If you click it again, it will turn grey again and delete the Like.
Code:
<style>
.my-like {
    background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABMAAAARCAYAAAA/mJfHAAABH0lEQVQ4y62T30vCUBiGv/9YuhBLkCA08FdogRFFYFEUhhZNCCQoSESiIOii68pl5qV6s8Eb7+SMHXNs6S7ejZ3zvA+ccT4BICofvS88dJ7w8vqG8WQC754K17lPjrx3z3l8D4YoVaqIrWbcJNbzaHefNZjfXPdy5b0jsO/IRqMxUpmSBnhz2bx1QL79GPbpEePmzhdSyW8fBDL0SK68HwiGCT2S3NiKREaPzP7QRRNPZSHpwm4kMnqkYbQikdEjZv8HK2ubS4nY75mD6WU8qzeXkrHvToBlWSjuHC4kYo99V8bwBnM0/iMiz542myq2bSPskcmR/zPos7lvP8Lv/nGd+/N6c2Xq2KcXhiY6qV1rxwotU3n/NHF8fgW+g9hfsHJlJUYljcgAAAAASUVORK5CYII=) !important;
    height:17px;
    width:19px;
    cursor:pointer;
    display:inline-block;
    vertical-align:top;
}
.my-liked, .my-like:hover {
    background-image: url(data:image/png;base64,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) !important;
    height:17px;
    width:19px;
    cursor:pointer;
    display:inline-block;
    vertical-align:top;
}
</style>
<script>
window.onload = function () {
document.body.insertAdjacentHTML( 'beforeEnd', '<iframe id="my-like-frame" style="display:none;"></iframe>' );
document.addEventListener( 'click', function ( event ) {
    var myLike = event.target;
    if( myLike.className.indexOf( 'my-like' ) > -1 ) {
        var frame = document.getElementById( 'my-like-frame' ),
            liked = ( myLike.className == 'my-liked' ),
            command = liked ? 'unlike' : 'like',
            reblog = myLike.getAttribute( 'data-reblog' ),
            id = myLike.getAttribute( 'data-id' ),
            oauth = reblog.slice( -8 );
        frame.src = 'http://www.tumblr.com/' + command + '/' + oauth + '?id=' + id;
        liked ? myLike.className = 'my-like' : myLike.className = 'my-liked';
    };
}, false );
};
</script>

Then cut and paste the following button code into your theme where you want your like button to be (this must be inside your {block:Posts} block). 
Code:
<div class="my-like" data-reblog="{ReblogURL}" data-id="{PostID}"></div>

A:

From the page, they're using the javascript:
$('a.like-link').click(function() {
    var post = $(this).closest('.post');
    var id = post.attr('id');
    var oath = post.attr('rel').slice(-8);
    var like = 'http://www.tumblr.com/like/'+oath+'?id='+id;
    $('#likeit').attr('src', like);
}

So post is just the HTML element of the post, they then simply get the id of that post and the 8 char code needed to like or reblog a post. They take all this, throw it into a URL and set it to the source of an iFrame on the page (#likeit)

