[Vuejs]-Want to show loading text before submitting using Vue.js

the customer data element is not mentioned in data object property, so your code should be like :

 <button type="button" @click="addCustomers" 
 :disabled="disableSubmitButton" class="btn btn-primary" style="float: 
 right;" value="ADD CUSTOMER">{{loading ? "Loading..." : "ADD 
 CUSTOMER"}}</button> 

and in the methods:

 addCustomers(){
   this.loading = true;
    axios.post().then(res=>{
         this.loading=false;
       }).catch(err=>{
        //handle error
       })
  }