如何选择文本字段元素“member-name”?
function revealPaywall (){
const paywall = document.getElementById('paywall')
const name = localStorage.getItem("value");
//TO WRITE MULTILINE HTML IN JS, USE BACKTICKS `` TO CREATE A TEMPLATE LITERAL
if (localStorage.getItem("value") === null){
paywall.innerHTML =
`
<h1>This Is An Example Of A Paywall<h1>
<p>If you enter a name, it will be saved to the localStorage. To bypass just enter your name and click the "submit" button<p>
<label for="name">Member Name:</label>
<input type="text" id="member-name">
<br><br><br>
<button onclick="paywallComplete()">SUBMIT</button>
`
}
}
function paywallComplete (){
const paywallName = document.querySelector("#member-name");
if (paywallName.value === null){
window.alert('hi');
}
我选择正确吗?如果是这样,为什么我在单击“提交”按钮时没有收到“嗨”警报。我在文本字段为空的情况下按下它,所以我假设
paywallName.value === null
应该是真的。我尝试了 querySelector(
#member-name)
& querySelector(
member-name)
但没有成功。
在 JavaScript 中,当输入字段为空时,其值不是 null,而是空字符串 ("")。因此,当您检查 paywallName.value === null 时,对于空输入字段来说,它不会成立。
function paywallComplete() {
const paywallName = document.querySelector("#member-name");
if (paywallName.value === "") {
window.alert('hi');
}
}