tests: move to jest (#19)

* tests: move to jest

- also fixes security deps
- replace eslint with standard

* fix: add engines

* chore: update keywords

.travis.yml

@@ -1,4 +1,4 @@
 language: node_js
 node_js:
-  - '8'
   - '10'
+  - '12'

lib/haversine.js

@@ -1,9 +1,20 @@
 // inspired from package haversine originally By Nick Justice (niix) at https://github.com/niix/haversine
-function toRadian(num) {
+
+/**
+ * converts a number to radian value
+ * @param {number} num a number
+ */
+function toRadian (num) {
   return (num * Math.PI) / 180
 }
 
-function distance(start, end, options = {}) {
+/**
+ * finds the distance between two lat-long values
+ * @param {object} start start lat-long
+ * @param {object} end end lat-long
+ * @param {object} options any options
+ */
+function distance (start, end, options = {}) {
   // init constants
   const km = 6371
   const mile = 3960

lib/reverse-geocode.js

@@ -1,13 +1,13 @@
 const haversine = require('./haversine')
 
 /**
- * iterates over locations to find closest location to given input lat-lon values
+ * iterates over locations to find closest location to given input lat-long values
  * @param  {Number} latitude  latitude value
  * @param  {Number} longitude longitude value
  * @param  {String} countryCode Country Code. Should exist in /locations/{countryCode}.json
  * @return {Object}           city data in an object
  */
-function lookup(latitude, longitude, countryCode) {
+function lookup (latitude, longitude, countryCode) {
   let minDistance = Infinity
   let city = {}
 
@@ -17,7 +17,7 @@ function lookup(latitude, longitude, countryCode) {
   // iterate through all locations
   try {
     const otherCountryOrigin = require(`../locations/${countryCode}.json`)
-    otherCountryOrigin.forEach((location) => {
+    otherCountryOrigin.forEach(location => {
       const distance = haversine.distance(start, location)
       if (distance < minDistance) {
         city = location