[英]Can't find a way to refactor alert (exercise)
我是一個JS noob試圖讓這個“你好mr./miss yourname ！” 清潔。 我沒有看到在if / else中重構警報的方法，因為那時我失去了var b的值。
JS：
<script>
"use strict";
window.onload = function () {
let form1 = document.getElementById('myForm');
form1.addEventListener('submit', helloYou);
function helloYou() {
let x = document.getElementById("1").value;
let a = document.getElementById('3').value;
if ( a === "M") {
let b = "Mr.";
alert('Hello ' + b + " " + x + "!");
}
else {
let b = "Miss";
alert('Hello ' + b + " " + x + "!");
}
}
}
</script>
HTML：
<body>
<form id="myForm">
Write your name:
<input type="text" name="yourname" id="1" placeholder="name">
<select name="gender" id="3">
<option value="M">Male</option>
<option value="F">Female</option>
<input type="submit" name="submission" id="2" value="TRY ME">
</form>
</body>
謝謝你的任何建議。
您可以使用三元運算符
alert('Hello ' + ( a === "M" ? "Mr." : "Miss" ) + " " + x + "!");
即
function helloYou() {
let x = document.getElementById("1").value;
let a = document.getElementById('3').value;
alert('Hello ' + ( a === "M" ? "Mr." : "Miss" ) + " " + x + "!");
}
假設您只需要為警報選擇gender的值，您可以將值更改為Mr.和Miss然后只提醒/打印它們。
<script>
"use strict";
window.onload = function () {
let form1 = document.getElementById('myForm');
form1.addEventListener('submit', helloYou);
function helloYou() {
let x = document.getElementById("1").value;
let a = document.getElementById('3').value;
alert('Hello ' + a + " " + x + "!");
}
}
</script>
HTML
<body>
<form id="myForm">
Write your name:
<input type="text" name="yourname" id="1" placeholder="name">
<select name="gender" id="3">
<option value="Mr.">Male</option>
<option value="Miss">Female</option>
<input type="submit" name="submission" id="2" value="TRY ME">
</form>
</body>
function helloYou() {
const val = id => document.getElementById(id).value;
alert(`Hello ${val(3) === "M" ? "Mr." : "Miss"} ${val(1)} !`);
}
我們可以利用兩件事1 tenary來縮短你的邏輯。
condition ? result : otherResult
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Conditional_Operator
和模板文字，它允許你使用back tics將javascript添加到字符串`string $ {javascript}``
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals
像這樣的東西？
<script>
"use strict";
window.onload = function () {
let form1 = document.getElementById('myForm');
form1.addEventListener('submit', helloYou);
function helloYou() {
let x = document.getElementById("1").value;
let a = document.getElementById('3').value;
let b = "Miss"
if ( a === "M") {
b = "Mr.";
}
alert('Hello ' + b + " " + x + "!");
}
}
</script>
只需添加此選項，相當干凈:)
const helloYou = () => {
let name = document.getElementById('1').value
let gender = document.getElementById('3').value
const prefix = gender === 'M' ? 'Mr.' : 'Miss'
alert(`Hello ${prefix} ${name}!`)
}
找不到有關koa.js工作坊解決方案的說明，練習一
[英]Can't find an explanation for koa.js workshop solution, exercise number one
使用 Expo “ReferenceError：找不到變量：警報”反應本機
[英]React Native with Expo “ReferenceError: Can't find variable: Alert”
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