JavaScript基础应用：改变内容、样式及输入验证-优快云博客

本文展示了JavaScript如何实现基本功能，包括修改HTML内容、改变样式以及进行输入验证，通过实例代码深入浅出地介绍了这些操作。

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javascript可以用来做的三件最基础的事

1.改变html中的内容

2.改变html中的样式

3.对输入检测

下面是案例

<!DOCTYPE html>
<html>
<body>
***************************************************************************************************
<h1>JavaScript Can Change Images</h1>

<img id="myImage" onclick="changeImage()" src="pic_bulboff.gif" width="100" height="180">

<p>Click the light bulb to turn on/off the light.</p>
***************************************************************************************************
<br>
<h1>What Can JavaScript Do?</h1>

<p id="demo1">JavaScript can change the style of an HTML element.</p>
<button type="button" onclick="myFunction()">Click Me!</button>
<br>
***************************************************************************************************
<h1>JavaScript Can Validate Input</h1>

<p>Please input a number between 1 and 10:</p>

<input id="numb" type="number">

<button type="button" onclick="validate()">Submit</button>

<p id="demo2"></p>
<script>
function changeImage() {
    var image = document.getElementById('myImage');
    if (image.src.match("bulbon")) {
        image.src = "pic_bulboff.gif";
    } else {
        image.src = "pic_bulbon.gif";
    }
}
function myFunction() {
    var x = document.getElementById("demo1");
    x.style.fontSize = "25px";           
    x.style.color = "red"; 
}
function validate() {
    var x, text;

    // Get the value of the input field with id="numb"
    x = document.getElementById("numb").value;

    // If x is Not a Number or less than one or greater than 10
    if (isNaN(x) || x < 1 || x > 10) {
        text = "Input not valid";
    } else {
        text = "Input OK";
    }
    document.getElementById("demo2").innerHTML = text;
}
</script>

</body>
</html>