setInterval doesn't fire in vue - vue.js

Question

im learning vue and setInterval doesn't work like in normal javascript? the problem is that my update function doesn't get fired.
start gets fired from a button, and hours/minutes/seconds are bound to input fields with v-model, i get all console.logs before the setInterval.
export default Vue.extend({
name: "timer-c",
data() {
return {
startDate: undefined,
hours: "",
minutes: "",
seconds: "",
timeLeft: undefined,
endDate: undefined,
interval: undefined,
text: "00:00:00",
sub: undefined,
};
},
methods: {
start: function() {
if (this.sub === undefined) {
let sum = 0;
if (this.seconds.match(/^\d+$/)) {
sum = sum + this.seconds * 1000;
console.log(sum);
}
if (this.minutes.match(/^\d+$/)) {
sum = sum + this.minutes * 60 * 1000;
}
if (this.hours.match(/^\d+$/)) {
sum = sum + this.hours * 60 * 60 * 1000;
}
if (sum === 0) {
console.log(this.$refs.br_start);
this.failed = true;
} else {
console.log(sum);
this.failed = false;
this.endDate = new Date(Date.now() + sum);
console.log(this.endDate);
this.startDate = new Date(Date.now());
console.log(this.startDate);
this.interval = setInterval(time => this.update, 1000);
//this.sub = this.interval.subscribe(time => this.update(time));
}
}
},
update: function() {
console.log('test');
const timeRemaining = Math.round((Date.now() - this.endDate) / 1000);
this.text = timeRemaining;
if (new Date(Date.now()) >= this.endDate) {
console.log("test");
}
},

Answer 1

Try to not return the function but execute it
this.interval = setInterval(time => { this.update(time) }, 1000);