19-20-arrow-function-this.js

var arrowThis = {
    handleBlurOld: function(fieldName, value) {  
        var self = this;
        //...
        //...
        this.doSomething(fieldName, value, function(err, json) {
            self.doAnotherthing(function(err, response) {
                //...
                //...
        });
      });
    },
    handleBlurNew: function(fieldName, value) {
        //...
        //...
        this.doSomething(fieldName, value, (err, json) => {
            this.doAnotherthing((err, response) => {
                //...
                //...
            });
        });
    }
}