why property of object is undefined when refered by "this"

Question

var regionUtils = {
  getNameByCode: function(code){
        var name = "ERROR";
        console.log("in getNameByCode :" + this.regions);// here this.regions is undefined.
        for(var i=0;i<this.regions.length;i++){
            if(this.regions[i]['code'] === code){
                name = this.regions[i]['name'];
            }
        }
        return name;

  },
  regions:[
        {
            "name": "Afghanistan",
            "alpha2": "AF",
            "alpha3": "AFG",
            "numeric": "004"
        },
        {
            "name": "Åland Islands",
            "alpha2": "AX",
            "alpha3": "ALA",
            "numeric": "248",
            "altName": "Aland Islands"
        },
  ],
};

export default regionUtils;

And in other scripts when I imported the above util and trying to use the method getNameByCode and find this.regions is undefined.

I am using this function in a VUE script like this:

import RegionUtils from '@/utils/regionUtils'
export default {
    methods:{
      getCodeByName: RegionUtils.getCodeByName,
    }
}

and using that in my template

<td><div v-for="item in scene.regions" :key="item.name">{{getNameByCode(item)}}</div></td>

works fine when `regionUtils.getNameByCode('COD')` is called [fiddle](https://jsfiddle.net/shrys/2u130gmr/) — shrys, Mar 16 '20 at 11:02
@shrys, sorry if any confusing but I have just edited my question. — armnotstrong, Mar 16 '20 at 11:05
use fat arrow syntax for that function declaration inside the object; `getNameByCode: (code) => { ` — Mechanic, Mar 16 '20 at 11:08
@deceze yeah, thats strange, the only way i found is hard binding; `regionUtils.getNameByCode('COD').apply(regionUtils)` — Mechanic, Mar 16 '20 at 11:19
@Captain It's not strange, it's how it is. `() => ...` binds `this` to what `this` is in the context the method is written in; in this case `window` or something like that. You better read that duplicate as well. The concrete answer here is `{ getCodeByName: RegionUtils.getCodeByName.bind(RegionUtils) }`. — deceze, Mar 16 '20 at 11:23

why property of object is undefined when refered by "this"

0 Answers0