仅使用 JavaScript 单击按钮即可增加字体大小 [英] Increase the font size with a click of a button using only JavaScript
问题描述
我试图通过单击按钮来增加字体大小.我已经让第一个工作了,但我无法理解第二个.第二个,每次点击都会增加1px的字体(我几乎卡住了):
I'm attempting to increase the font size with the click of a button. I have got the first one to work but I can't get my head around the second one. The second one, every click will increase the font by 1px (I'm pretty much stuck):
<input type="button" value="Increase Font Size 100px" onclick="increaseFontSizeBy100px()">
<p id="a">Font Size</p>
<input type="button" value="Increase Font Size 1px" onclick="increaseFontSizeBy1px()">
<p id="b">Font Size by 1 Pixel</p>
<script>
function increaseFontSizeBy100px() {
document.getElementById('a').style.fontSize = "100px";
}
function increaseFontSizeBy1px() {
var font = document.getElementById('b').style.fontSize;
font++;
}
</script>
推荐答案
将您的函数更改为如下代码所示,看看会发生什么:
Change your function to as in the code below and see what happens:
function increaseFontSizeBy100px() {
txt = document.getElementById('a');
style = window.getComputedStyle(txt, null).getPropertyValue('font-size');
currentSize = parseFloat(style);
txt.style.fontSize = (currentSize + 100) + 'px';
}
function increaseFontSizeBy1px() {
txt = document.getElementById('b');
style = window.getComputedStyle(txt, null).getPropertyValue('font-size');
currentSize = parseFloat(style);
txt.style.fontSize = (currentSize + 1) + 'px';
}
注意:如您所见,这两个函数都存在大量重复.因此,如果我是你,我会更改此函数以将 fontsize 增加给定值(在本例中为 int).
Note: as you can see, there are a lot of duplication in both functions. Therefore, if I were you, I would change this function to increase the fontsize by a given value(in this case, an int).
那么,我们能做些什么呢?我认为我们应该把这些功能变成一个更通用的功能.
So, what we can do about it? I think we should turn these functions into a more generic one.
看看下面的代码:
function increaseFontSize(id, increaseFactor){
txt = document.getElementById(id);
style = window.getComputedStyle(txt, null).getPropertyValue('font-size');
currentSize = parseFloat(style);
txt.style.fontSize = (currentSize + increaseFactor) + 'px';
}
现在,例如,在您的按钮增加字体大小 1 像素"中,您应该输入如下内容:
Now, for example, in your button "Increase Font Size 1px", you should put something like:
<input type="button" value="Increase Font Size 1px" onclick="increaseFontSize("b", 1)">
<p id="b">Font Size by 1 Pixel</p>
但是,如果我们想要减小字体大小 1px",我们可以做什么?我们用 -1 而不是 1 来调用函数.
But, if we want a "Decrease Font Size 1px", what we can do? We call the function with -1 rather than with 1.
<input type="button" value="Decrease Font Size 1px" onclick="increaseFontSize("b", -1)">
<p id="b">Font Size by -1 Pixel</p>
我们也解决了减小字体大小问题.但是,我会将函数名称更改为更通用的名称,并在我将创建的两个函数中调用它:increaseFontSize(id, increaseFactor) 和 decreaseFontSize(id, reductionFactor)强>.
We solve the Decrease Font Size problem as well. However, I would change the function name to a more generic one and call it in both two functions that I would create: increaseFontSize(id, increaseFactor) and decreaseFontSize(id, decreaseFactor).
就是这样.
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