How to calculate two input values and put the result in another input field in Vue,js?

Question

Here are my input fields:

Answer 1

if you really want to keep your form object you'll need to write your own event handler instead of using v-model

https://jsfiddle.net/575dtfqz/1/

javascript:

methods: {
    updateQuantity(event) {
        this.form.sale_quantity = event.target.value
        this.form.sale_total = this.form.sale_quantity * this.form.sale_rate
    },
    updateRate(event) {
        this.form.sale_rate = event.target.value
        this.form.sale_total = this.form.sale_quantity * this.form.sale_rate
    }
}