Apply a discount using VueJS and Laravel

I haven't gone down the road of creating custom components, I have got it checking for the coupon code now I need to know how I can set a the cost then apply the discount.

Heres the JS I have currently

new Vue({
el: '#coupons',

data: function() {
    return {
        coupon: {
            code: '',
            description: '',
            discount: 0
        },

        valid: false
    };
},

methods: {
    validate: function() {
        this.$http.get('/coupons/' + this.coupon.code)
            .success(function(coupon) {
                this.coupon = coupon;
                this.valid = true;
                this.coupon.description = 'Great! You entered a valid coupon.';

            })
            .error(function() {
                this.coupon.code = '';
                this.coupon.description = 'Sorry, that coupon does not exist.';
            });
    }
}
});

Anyone advise on how to achieve this based on the above please :) Presumably I would need to pass the value from Laravel to the JS, again how would I achieve this, then apply the discount, would I se v-model for example to use two way binding?

via Chebli Mohamed