JavaScript 函数和按钮

Question

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Answer 1

你在 myFunction2 中有错字

getElementById
             ^ small letter

和

document.getElementById("demo2").style.backgroundColor = "yellow";
                                       ^^^^^^^^^^^^^^^ a single property with capital
                                                       letter instead of dash

function myFunction() {
    document.getElementById("demo").innerHTML = "Hello JavaScript!";
}

function myFunction2() {
    document.getElementById("demo2").style.fontSize = "25px";
    document.getElementById("demo2").style.color = "red";
    document.getElementById("demo2").style.backgroundColor = "yellow";
}

<p id="demo">This is a demonstration.</p>
<button onclick="myFunction()">Click Me!</button>

<p id="demo2">JavaScript can change the style of an HTML element.</p>
<button onclick="myFunction2()">Click me!</button>