未捕獲的TypeError：無法設置未定義的屬性“背景”

Question

我正在嘗試在頁面加載時加載CSS背景圖像，但出現此錯誤

未捕獲的TypeError：無法設置未定義的屬性“背景”

function loadBG() {
    document.getElementsByClassName("img-icon-invite").style.background = "url('<?php echo Yii::app()->theme->baseUrl; ?>/style/home/images/firstProPopup-sprite-new-white.png')";
    document.getElementsByClassName("img-icon-verified").style.background = "url('http://dev1.venturepact.com/themes/adminre/style/home/images/firstProPopup-sprite-new-white.png')";
}

window.onload = loadBG();

Answer 1

由於getElementsByClassName返回元素數組，因此您也需要指定索引，

document.getElementsByClassName("img-icon-invite")[0].style.background="url('<?php echo Yii::app()->theme->baseUrl;?>/style/home/images/firstProPopup-sprite-new-white.png')";

或者您可以使用Jquery

$(".img-icon-invite").css('background-image', 'url(' + imageUrl + ')');

Answer 2

正如您提到的jQuery：

function loadBG(){
        $(".img-icon-invite").css('background-image', "url('<?php echo Yii::app()->theme->baseUrl;?>/style/home/images/firstProPopup-sprite-new-white.png')";
        $(".img-icon-verified").css('background-image',"url('http://dev1.venturepact.com/themes/adminre/style/home/images/firstProPopup-sprite-new-white.png')";

}
$(document).ready(loadBG);