我想计算出一个的行高<p>div 内的标签。
var myp = document.getElementById('myp');
var heightLabel = document.getElementById('heightLabel');
heightLabel.innerHTML = myp.style.lineHeight + " is the height."; <div>
<p id=myp>People assume I'm a boiler ready to explode, <br>but I actually have very low blood pressure, <br>which is shocking to people.</p>
</div>
<h3 id="heightLabel"></h3>但是，如上面的代码所示，如果未显式分配 p 标记的行高，则使用.style.lineHeight返回一个空字符串。
有没有什么办法可以得到一行的高度<p>如果尚未分配标签？我想最后以 px 为单位。
代替.style财产，你需要getComputedStyle()你的p element
var elementStyle = window.getComputedStyle(*DOM element*);
之后你可以简单地使用elementStyle.getPropertyValue(*style-property*) prop.
顺便提一句。您可以在控制台下检查计算的样式（firefox 屏幕截图）：
请参阅工作示例：
var myp = document.getElementById('myp');
var heightLabel = document.getElementById('heightLabel');
var mypStyle = window.getComputedStyle(myp);
heightLabel.innerHTML = mypStyle.getPropertyValue('line-height') + " is the line height.";
// console.log(mypStyle.getPropertyValue('line-height')); // output 20px
// console.log(typeof mypStyle.getPropertyValue('line-height')); // string
// Using parseFloat we convert string into value
// Examples:
// parseFloat('20px') // 20, typeof number
// parseFloat('22.5rem') // 22.5 typeof number
// If you are sure, your string will always contain intenger value use parseInt() instead
// DOES not work cross-browser
// Chrome return line-height normal, firefox '20px'
// var getNumberValue = parseFloat(mypStyle.getPropertyValue('line-height')); // 20, typeof string
console.log(getLineHeight(myp));
// https://stackoverflow.com/questions/4392868/javascript-find-divs-line-height-not-css-property-but-actual-line-height?noredirect=1&lq=1
function getLineHeight(element){
var temp = document.createElement(element.nodeName);
temp.setAttribute("style","margin:0px;padding:0px;font-family:"+element.style.fontFamily+";font-size:"+element.style.fontSize);
temp.innerHTML = "test";
temp = element.parentNode.appendChild(temp);
var ret = temp.clientHeight;
temp.parentNode.removeChild(temp);
return ret;
}<div>
<p id=myp>People assume I'm a boiler ready to explode, <br>but I actually have very low blood pressure, <br>which is shocking to people.</p>
</div>
<h3 id="heightLabel"></h3>