While computed properties are more appropriate in most cases, there are times when a custom watcher is necessary. That’s why Vue provides a more generic way to react to data changes through the watch option. This is most useful when you want to perform asynchronous or expensive operations in response to changing data. VueJS Watchers
html
<div id="watch_example">
Killograms : <input type="text" v-model="kilograms">
Pounds : <input type="text" v-model="pounds">
</div>
javascript
var vm = new Vue({
el: '#watch_example',
data: {
kilograms : 0,
pounds: 0
},
methods: {
},
computed :{
},
watch : {
kilograms: function(val) {
this.kilograms = val;
this.pounds = val * 0.453592;
}
}
});