Question

使用javascript函数写入HTML id img标签时遇到问题。在javascripts函数＆＃34; pageSetup＆＃34;我试着写HTML＆＃34; IMG＆＃34;包含随机pic.Bellow的标签我列出了HTML代码和附加到HTML的功能。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
    <link href="flowers.css" rel="stylesheet" type="text/css"/>
    <script src="lab09.js" type="text/javascript"></script>
    <script type="text/javascript">
        window.onload = pageSetup();

            function pageSetup() {
                var nDate = new Date();
                var myBanner = displayBanner(nDate);
                alert(myBanner); /*This seems correct, returning a random
                                  picture 

                //document.getElementById(myBanner).src=
                var salesMessage = calcDaysToSale(nDate);
            }

    </script>

</head>
<body>
<div id="container">
    <div id="header">
        <p>
            <img id="myBanner" src=" " alt="Carol's Flowers"/>
        </p>

function displayBanner(currentDate) {
    var imgsource;
    var month;
    month = currentDate.getMonth()+1;
    if ((month==12)|| (month==1) || (month==2)){
        imgsource ="winterLogo.gif";
    }
    else if ((month==3) || (month==4) || (month==5)) {
        imgsource ="springLogo.gif";
    }
    else if ((month==6) || (month==7) || (month==8)) {
        imgsource ="summerLogo.gif";
    }
    else if ((month==9) || (month==10) || (month==11)) {
        imgsource ="fallLogo.gif";
    }
    else {
        imgsource = "defaultLogo.gif";
    }
    alert( imgsource );
    return imgsource;
}

Answer 1

您正在将图像源传递给getElementById（）。你不应该通过'myBanner'吗？和getElementById('myBanner').src = myBanner一样？

以下是使用您的代码的工作示例：

function displayBanner(currentDate) {
    var imgsource;
    var month;
    month = currentDate.getMonth()+1;
    if ((month==12)|| (month==1) || (month==2)){
      imgsource ="http://placehold.it/200?text=winterLogo.gif";
    }
    else if ((month==3) || (month==4) || (month==5)) {
      imgsource ="http://placehold.it/200?text=springLogo.gif";
    }
    else if ((month==6) || (month==7) || (month==8)) {
      imgsource ="http://placehold.it/200?text=summerLogo.gif";
    }
    else if ((month==9) || (month==10) || (month==11)) {
      imgsource ="http://placehold.it/200?text=fallLogo.gif";
    }
    else {
      imgsource ="http://placehold.it/200?text=defaultLogo.gif";
    }
    alert( imgsource );
    return imgsource;
}

var src = displayBanner(new Date());
document.getElementById('myBanner').src = src;

 <img id="myBanner" src=" " alt="Carol's Flowers"/>

JavaScript的;变量函数返回，写入HTML

1 个答案: