JAVASCRIPT

add css in javascript

document.getElementById("demo").style.display = "none";

how to give css style in javascript

document.getElementById("myH1").style.color = "red";

Set CSS styles with javascript

var style = document.createElement('style');
  style.innerHTML = `
  #target {
  color: blueviolet;
  }
  `;
  document.head.appendChild(style);

Set CSS styles with javascript

// Create our shared stylesheet:
const sheet = new CSSStyleSheet();
sheet.replaceSync('#target {color: darkseagreen}');

// Apply the stylesheet to a document:
document.adoptedStyleSheets = [sheet];

Set CSS styles with javascript

var style = document.createElement('style');
  document.head.appendChild(style);
  style.sheet.insertRule('#target {color: darkseagreen}');

Set CSS styles with javascript

document.getElementById('target').style.color = 'tomato';