[英]javascript function call returns undefined and page continouly loads
I have a HTML code as follows 我有一个HTML代码如下
<!DOCTYPE html>
<html>
<body>
<button type="button" onclick="loadDoc()">ALERT DATA</button>
<script>
function loadDoc() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function()
{
if (xhttp.readyState == 4 && xhttp.status == 200)
{
eval(xhttp.responseText);
}
};
xhttp.open("GET", "sample1.js", true)
xhttp.send();
}
</script>
</body>
</html>
Using the AJAX call I am able to call a javascript alert func 使用AJAX调用,我可以调用javascript警报函数
function callMe(){
alert("DATA IS 5");
}
document.write(callMe());
When I am running this simple HTML file on firefox it gives me "undefined" on the browser. 当我在firefox上运行此简单的HTML文件时,它在浏览器上给我“未定义”的信息。 I dont really understand why.I returned "" from the function callMe() so that removed the "undefined" on the browser but the page seems to be keep on loading . 我真的不明白为什么。我从函数callMe()返回了“”,以便删除了浏览器中的“未定义”,但页面似乎仍在继续加载。 Is there anything I am doing wrong ? 我做错了什么吗?
Your method callMe() evaluates to undefined (since it doesn't return anything and alert(...) -being the last command- will evaluate to undefined). 您的方法callMe()的评估结果为undefined(因为它不返回任何内容,并且alert(...)-作为最后一条命令-的评估结果为undefined)。
Therefore you will be writing "undefined" to your document. 因此,您将在文档中写入“未定义”。
Thanks for your support . 谢谢你的支持 。
I re wrote the js code as follows 我重新编写了js代码,如下所示
function callMe(){
alert("DATA IS 5");
return " ";
}
document.write(callMe());
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