我在四处寻找更多的JS。我想做一个简单的if / else语句来获取一个段落的文本,以改变一个字符串是否为空。
问题在于,两种情况下的语句均无法正确执行。实际上,它仍然保留最初显示的相同文本。
这是我的代码:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Time to practice: Adding elements with Javascript</title>
</head>
<body>
<main>
</main>
<script>
document.body.style.cssText = 'height: 100vw; width: 100vw';
var main = document.body.children[0].style.cssText = 'background-color: white; height: 100vw; width: 100vw';
var style = document.createElement('style');
style.innerHTML = `
#mainP {
font-size: 100px;
}`
;
document.head.appendChild(style);
var name = prompt("What's your name?");
var newP = document.createElement('p');
newP.setAttribute('id', 'mainP');
document.body.children[0].appendChild(newP);
console.log(name);
if (name === null) {
document.getElementById('mainP').innerHTML = "I didn't even want to know your name ";
} else {
document.getElementById('mainP').innerHTML = 'Hello ' + name + '.' + ' Hope you are having an awesome day!';
}
</script>
</body>
</html>
在条件语句if(name == null)中,出于某种原因将null转换为字符串。如果将语句更改为if(name =='null'),它将按预期工作。