function getElementsByClassName(className, tag, elm){
	var testClass = new RegExp("(^|s)" + className + "(s|$)");
	var tag = tag || "*";
	var elm = elm || document;
	var elements = (tag == "*" && elm.all)? elm.all : elm.getElementsByTagName(tag);
	var returnElements = [];
	var current;
	var length = elements.length;
	for(var i=0; i<length; i++){
		current = elements[i ];
		if(testClass.test(current.className)){
			returnElements.push(current);
		}
	}
	return returnElements;
}

function resizeImage() {
	var isize=getElementsByClassName('img_gauche','div').width;
	
	if (isize > 160) {
		isize = isize / 2;
	}
	alert (isize);
	
	return isize;
}