仅使用 JavaScript 单击按钮即可增加字体大小

Increase the font size with a click of a button using only JavaScript

提问by canecorso

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):

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，每次点击都会使字体增加 1px（我几乎卡住了）：

<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>

回答by Lucas Dias

Change your function to as in the code below and see what happens:

将您的函数更改为如下代码所示，看看会发生什么：

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';
}

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).

注意：如您所见，这两个函数都有很多重复。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）。

So, what we can do about it? I think we should turn these functions into a more generic one.

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。

Take a look at the code below:

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';
}

Now, for example, in your button "Increase Font Size 1px", you should put something like:

现在，例如，在您的按钮"Increase Font Size 1px" 中，您应该输入以下内容：

<input type="button" value="Increase Font Size 1px" onclick="increaseFontSize("b", 1)">
<p id="b">Font Size by 1 Pixel</p>

But, if we want a "Decrease Font Size 1px", what we can do? We call the function with -1 rather than with 1.

但是，如果我们想要一个"Decrease Font Size 1px"，我们能做什么？我们用 -1 而不是 1 来调用函数。

<input type="button" value="Decrease Font Size 1px" onclick="increaseFontSize("b", -1)">
<p id="b">Font Size by -1 Pixel</p>

We solve the Decrease Font Size problemas 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).

我们也解决了减小字体大小的问题。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reductionFontSize(id, reductionFactor)。

That's it.

就是这样。

回答by Jacoby Yarrow

Try this:

尝试这个：

<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 id = document.getElementById('b');
        var style = window.getComputedStyle(id, null).getPropertyValue('font-size');
        var currentSize = parseInt(style);
        currentSize++;
        document.getElementById('b').style.fontSize = currentSize.toString();
    }
</script>

回答by Rinto Antony

Simple query

简单查询

Font Size

字体大小

<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 = parseInt($("#b").css('font-size'));

    font++;
     document.getElementById('b').style.fontSize =font+ "px";
    }
</script>

回答by Walter de Jong

Cycle through different font sizes by clicking on an element

通过单击元素在不同的字体大小之间循环

$(document).ready(function() {
  $("#ModelIDBarcode").click(function() {
    newFontSize = incSize($('.barcode').css("font-size"), 10, 5, 120)
    $('.barcode').css("font-size", newFontSize);
  });
});

function incSize(currentSize, incr, min, max) {
  fSize = (parseFloat(currentSize) + incr) % max + min;
  return (fSize) + 'px';
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<label title="Click to increase size" id="ModelIDBarcode" class="barcode" style="font-family:'3 of 9 Barcode'; font-size:10px; background-color:white">
*ABarcodeValue*
</label>

回答by chaman gupta

$(document).ready(function() {
  $("#ModelIDBarcode").click(function() {
    newFontSize = incSize($('.barcode').css("font-size"), 10, 5, 120)
    $('.barcode').css("font-size", newFontSize);
  });
});

function incSize(currentSize, incr, min, max) {
  fSize = (parseFloat(currentSize) + incr) % max + min;
  return (fSize) + 'px';
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<label title="Click to increase size" id="ModelIDBarcode" class="barcode" style="font-family:'3 of 9 Barcode'; font-size:10px; background-color:white">
*ABarcodeValue*
</label>

回答by Mamunur Rashid

const button = document.querySelector('.bigger');
button.addEventListener('click', function(e) {
  const newFontSize =
    parseFloat(getComputedStyle(e.currentTarget).fontSize) + 1;
  e.currentTarget.style.fontSize = `${newFontSize}px`;
});