How do i change html class with javascript?

Question

I have a img tag with A class how to change it to B class

Answer 1

can i select class from option value?

Answer 2

I like the addEventListener approach. I was thinking of doing something like this:

<select onchange="update(this)"> ... </select>

function update(elSelected) {
alert(elSelected.value); // "red", "blue"
}

Embedding javascript in HTML is not the most clear, but I think there's an "onchange" event (not tested before posting, just an idea for you two)

Answer 3

im sorry...
how to change P class from red to blue if i choose Blue in select option

<select name="color">
<Option value="red">Red</option>
<option value="blue">Blue</option>
</select>

<p class="Red>
change to blue</p>

Answer 4

Ah, try something like this. The code basically adds a listener to the select, so every time you click on it it will verify what you selected and change the class.

var select = document.getElementById('example'); //Again, you can get the item as you like, I do it for convenience
select.addEventListener('click', function() {
var selectedOption = this.options[select.selectedIndex];
var p = document.getElementsByTagName('p');

if (selectedOption.value == 'red') {
p[0].className = 'red';
} else {
p[0].className = 'blue';
}
});

Answer 5

JS:
document.getElementById("MyElement").className = "MyClass";

JQuery:
$('#MyElement').removeClass('MyOldClass');
$('#MyElement').addClass('MyClass');

(You can get the item by the name of the tag, the ID or the class. In this case I used the ID by habit)

Answer 6

I don't understand your question :/