Tumblr Post type Text, thumbnails

tumblr.js

/* Created by AlexR1712 */
function getImg (str) {
    var m,
        urls = [], 
        rex = /<img[^>]+src="(http:\/\/[^">]+)"/g;
    while ( m = rex.exec( str ) ) {
        urls.push( m[1] );
    }
    return urls;
}

var posts = document.querySelectorAll('.post-excerpt');
posts.forEach(function(body) {
    imgs = getImg(body.innerHTML);
    /* remove html tags */
    body.innerHTML = body.textContent;
    if (imgs.length > 0) {
        /* Set first image as default in view*/
        body.parentElement.parentElement.childNodes[0].src = imgs.shift();    
    }    
});