context "this" does not return correct

Question

When giving a console.log(this), I wanted the console’s THIS to return Vue, not Validate’s This,

this.$ValidateUtil({
        el: this.$refs.cadMain,
        rules: {
          cep: {
            required: true,
            regex: /^\d{5}-\d{3}$/
          }
        },
        messages: {
          cep: {
            regex: "CEP inválido"
          }
        },
        submitHandler: function () {
          // AQUI!! -->>console.log(this);
          return false;
        }
      })

import Vue from 'vue'
import 'jquery-validation'
var LibsUtil = (function () {
    function LibsUtil() {
    }
    LibsUtil.ValidateUtil = function (options) {
      options = options || {}
      $(options.el).validate({
        rules: options.rules || {},
        messages: options.messages || {},
        submitHandler: function (form) {
          if (typeof options.submitHandler !== 'undefined') {
            options.submitHandler(this, form)
          }
          return false;
        }
      })
      Return Vue;
    };

    LibsUtil.install = function (Vue) {
        Vue.ValidateUtil = LibsUtil.ValidateUtil;

        if (!Vue.prototype.hasOwnProperty("$ValidateUtil")) {
          Vue.prototype.$ValidateUtil = LibsUtil.ValidateUtil;
      }


    };
    return LibsUtil;
}());
export { LibsUtil };
export default LibsUtil;

Answer 1

It happens that there are moments in some functions that change the context of this, and so you can no longer access it, an example of this is the function setInterval, where within the execution of the function is changed the context, and with that you no longer have access to this of the instance, to resolve this you can do as follows:

todo(){  
    const self = this; //preserva instancia do this na variavel self    
    this.intervalid1 = setInterval(function(){
        self.changes = ((Math.random() * 100).toFixed(2))+'%';
        console.log (this.changes);
    }, 3000);
}

thus within the setInterval it is possible to use the instance of Vue with the variable "self", you can use this same strategy for this validation lib