To count text lines inside an DOM element with JavaScript, we can calculate it from the element height and its line height.
For instance, we write
const el = document.getElementById("content");
const divHeight = el.offsetHeight;
const lineHeight = parseInt(el.style.lineHeight);
const lines = divHeight / lineHeight;
console.log(lines);
to get the element with getElementById.
We get its height with offsetHeight.
We get its line height with el.style.lineHeight.
Then we divide divHeight by lineHeight to get the number of lines.
