How to fire an event when v-model changes?

You can actually simplify this by removing the v-on directives:

<input type="radio" name="optionsRadios" id="optionsRadios1" value="1" v-model="srStatus">

And use the watch method to listen for the change:

new Vue ({    el: "#app",    data: {        cases: [            { name: 'case A', status: '1' },            { name: 'case B', status: '0' },            { name: 'case C', status: '1' }        ],        activeCases: [],        srStatus: ''    },    watch: {        srStatus: function(val, oldVal) {            for (var i = 0; i < this.cases.length; i++) {                if (this.cases[i].status == val) {                    this.activeCases.push(this.cases[i]);                    alert("Fired! " + val);                }            }        }    }});

javascript events vue.js

This happens because your click handler fires before the value of the radio button changes. You need to listen to the change event instead:

<input   type="radio"   name="optionsRadios"   id="optionsRadios2"   value=""  v-model="srStatus"   v-on:change="foo"> //here

Also, make sure you really want to call foo() on ready... seems like maybe you don't actually want to do that.

ready:function(){    foo();},

javascript events vue.js

Vue2: if you only want to detect change on input blur (e.g. after press enter or click somewhere else) do (more info here)

<input @change="foo" v-model... >

If you wanna detect single character changes (during user typing) use

<input @keydown="foo" v-model... >

You can also use @keyup and @input events. If you wanna to pass additional parameters use in template e.g. @keyDown="foo($event, param1, param2)". Comparision below (editable version here)

Show code snippet

new Vue({  el: "#app",  data: {     keyDown: { key:null, val: null,  model: null, modelCopy: null },    keyUp: { key:null, val: null,  model: null, modelCopy: null },    change: { val: null,  model: null, modelCopy: null },    input: { val: null,  model: null, modelCopy: null },          },  methods: {      keyDownFun: function(event){                   // type of event: KeyboardEvent         console.log(event);        this.keyDown.key = event.key;                // or event.keyCode      this.keyDown.val = event.target.value;       // html current input value      this.keyDown.modelCopy = this.keyDown.model; // copy of model value at the moment on event handling    },        keyUpFun: function(event){                     // type of event: KeyboardEvent      console.log(event);        this.keyUp.key = event.key;                  // or event.keyCode      this.keyUp.val = event.target.value;         // html current input value      this.keyUp.modelCopy = this.keyUp.model;     // copy of model value at the moment on event handling    },        changeFun: function(event) {                   // type of event: Event      console.log(event);      this.change.val = event.target.value;        // html current input value      this.change.modelCopy = this.change.model;   // copy of model value at the moment on event handling    },        inputFun: function(event) {                    // type of event: Event      console.log(event);      this.input.val = event.target.value;         // html current input value      this.input.modelCopy = this.input.model;     // copy of model value at the moment on event handling    }  }})

div {  margin-top: 20px;}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>Type in fields below (to see events details open browser console)<div id="app">  <div><input type="text" @keyDown="keyDownFun" v-model="keyDown.model"><br> @keyDown (note: model is different than value and modelCopy)<br> key:{{keyDown.key}}<br> value: {{ keyDown.val }}<br> modelCopy: {{keyDown.modelCopy}}<br> model: {{keyDown.model}}</div>    <div><input type="text" @keyUp="keyUpFun" v-model="keyUp.model"><br> @keyUp (note: model change value before event occure) <br> key:{{keyUp.key}}<br> value: {{ keyUp.val }}<br> modelCopy: {{keyUp.modelCopy}}<br> model: {{keyUp.model}}</div>    <div><input type="text" @change="changeFun" v-model="change.model"><br> @change (occures on enter key or focus change (tab, outside mouse click) etc.)<br> value: {{ change.val }}<br> modelCopy: {{change.modelCopy}}<br> model: {{change.model}}</div>    <div><input type="text" @input="inputFun" v-model="input.model"><br> @input<br> value: {{ input.val }}<br> modelCopy: {{input.modelCopy}}<br> model: {{input.model}}</div>     </div>

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