Magento file size and file extensions frontend validation

gistfile1.js

Validation.addAllThese([
  ['validate-filesize','The file size should not exceed 100 kb.',function(v, elm){
		var maxSize = 102400;
        if (navigator.appName == "Microsoft Internet Explorer") {
        	if (elm.value) {
        		var oas = new ActiveXObject("Scripting.FileSystemObject");
        		var e = oas.getFile(elm.value);
        		var size = e.size;
        	}
        } else {
        	if (elm.files[0] != undefined) {
        		size = elm.files[0].size;
        	}
        }
        if (size != undefined && size > maxSize) {
        	return false;
        }
        return true;
    }],
    ['validate-fileextensions','Disallowed file type.',function(v, elm){
		var extensions = ['jpeg','gif'];
		if (!v) {
			return true;
		}
        with (elm) {
        	var ext = value.substring(value.lastIndexOf('.') + 1);
        	for (i=0; i < extensions.length; i++) {
        		if (ext == extensions[i]) {
        			return true;
        		}
        	}
        }
        return false;
    }],

]);