如何使用 Javascript 动态增加字体大小，为什么我当前的功能不起作用？
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How can I dynamically increase font size with Javascript and why is my current function not working?
提问by Kenny Johnson
I'm trying to increase the font size of my page using a javascript function but it's not working. Is there a syntax problem with my code or is it not possible to do what I'm trying to do?
我正在尝试使用 javascript 函数增加页面的字体大小，但它不起作用。我的代码是否存在语法问题，或者无法执行我正在尝试执行的操作？
Javascript:
Javascript：
function changeFontSize(fontvar) {
var div = document.getElementById("webchat_history");
var currentFont = div.style.fontSize.value;
div.style.fontSize = currentFont + fontvar+ "px";
}
HTML:<span onClick="changeFontSize(10);" style="font-size:16px;">Aa</span>
HTML：<span onClick="changeFontSize(10);" style="font-size:16px;">Aa</span>
I want to increase it by x amount (fontvar) rather than specifying a specific font size because my font sizes are set in an external stylesheet. When/if I need to modify the stylesheets, I'd rather not have to update the Javascript too.
我想将它增加 x 数量（fontvar）而不是指定特定的字体大小，因为我的字体大小是在外部样式表中设置的。当/如果我需要修改样式表，我也不想更新 Javascript。
回答by LRA
This script should work:
这个脚本应该可以工作：
function changeFontSize(fontvar) {
var div = document.getElementById("webchat_history");
var currentFont = div.style.fontSize.replace("px", "");
div.style.fontSize = parseInt(currentFont) + parseInt(fontvar) + "px";
}
回答by jumpHyman
I found this amazing script: https://github.com/simplefocus/FlowType.JS
我发现了这个惊人的脚本：https: //github.com/simplefocus/FlowType.JS
回答by Kenny Johnson
After additional debugging, I realized the "id" I was using, webchat_history, was not actually an ID. It was the classfor ID history. I'm going to create additional classes and use document.getElementById('history').className = "webchat_history_medium";to change font sizes.
经过额外的调试，我意识到我使用的“id”webchat_history实际上并不是一个 ID。它是ID的类history。我将创建其他类并用于document.getElementById('history').className = "webchat_history_medium";更改字体大小。
