For v3.x, click here. A common need for data binding is manipulating an element’s class list and its inline styles. Since they are both attributes, we can use v-bind to handle them: we only need to calculate a final string with our expressions.
However, meddling with string concatenation is annoying and error-prone. For this reason, Vue provides special enhancements when v-bind is used with class and style.
We can pass an object to v-bind:class to dynamically toggle classes:. The above syntax means the presence of the active class will be determined by the truthiness of the data property isActive. You can have multiple classes toggled by having more fields in the object.