how to replace class name in javascript code example

Example 1: js add class

var element = document.getElementById('element');
element.classList.add('class-1');
element.classList.add('class-2', 'class-3');
element.classList.remove('class-3');

Example 2: javascript change element class

//Overwrite all classes
element.className = "class";

//Add class
element.classList.add("class");

Example 3: change elements class javascript

document.getElementById("MyElement").classList.add('MyClass');

document.getElementById("MyElement").classList.remove('MyClass');

if ( document.getElementById("MyElement").classList.contains('MyClass') )
{
document.getElementById("MyElement").classList.toggle('MyClass');
}

Example 4: how to remove an class in javascript

document.getElementsByClassName("legend").style.display="none";