var post_div document getElementById id-div var imgs post_div getEleme

var post_div = document.getElementById("id-div"); 
var imgs = post_div.getElementsByTagName("img"); 
for (var i = 0; i < imgs.length; i++) { 
    imgs[i].onclick = function(){
        alert('click);
    }
    imgs[i].style.cursor = 'pointer';
}