feat(deps): Remove check-types in favor of lodash

Since the creation of this module we have largely settled on lodash as
our Javascript helper library of choice. This module was now using both,
which seemed excessive and inconsistent.

This change replaces all use of `check-types` with equivalent lodash
functionality.

One notable conceptual change is regarding what is valid to store in a
`Variable` object used as placeholder values in queries.

Initially, only scalar values were supported: non-empty strings,
numbers, and booleans.

However, over time we found it useful to store first arrays and then
even objects as variables, meaning its now clearer to enumerate what a
`Variable` _doesn't_ support storing: empty strings, `null`, and
`undefined`

lib/Variable.js

@@ -14,14 +14,14 @@
  *always* yield true; regardless of the underlying value; because js.
  **/
 
-var check = require('check-types');
+const _ = require('lodash');
 
 function Variable(){
   this.$ = '';
 }
 
 Variable.prototype.set = function( val ){
-  if( !check.nonEmptyString(val) && !check.number(val) && !check.boolean(val) && !check.array(val) && !check.object(val)){
+  if( val === '' || val === null || val === undefined ){
     throw new Error( 'invalid value, value must be valid js Variable' );
   }
   this.$ = val;

lib/VariableStore.js

@@ -5,12 +5,13 @@
   note: you may inject your own variables when calling the constructor
 **/
 
-var check = require('check-types'),
-    Variable = require('./Variable');
+const _ = require('lodash');
+
+const Variable = require('./Variable');
 
 function VariableStore( vars ){
   this._vars = {};
-  if( check.assigned( vars ) ){
+  if( !_.isEmpty( vars ) ){
     this.set( vars );
   }
 }
@@ -31,17 +32,19 @@ function VariableStore( vars ){
   vs.var('foo').set('bar');
 **/
 VariableStore.prototype.var = function( key, val ){
-  if( !check.nonEmptyString( key ) ){
+  if( _.isEmpty( key ) || !_.isString( key) )  {
     throw new Error( 'invalid query variable, key must be valid string' );
   }
   // init variable
   if( !this._vars.hasOwnProperty( key ) ){
     this._vars[ key ] = new Variable();
   }
-  // setter
-  if( check.assigned( val ) ){
+
+  // set value if val parameter passed
+  if (val !== undefined) {
     this._vars[ key ].set( val );
   }
+
   // getter
   return this._vars[ key ];
 };
@@ -50,7 +53,7 @@ VariableStore.prototype.var = function( key, val ){
   check if a key has been set (has a value)
 **/
 VariableStore.prototype.isset = function( key ){
-  if( !check.nonEmptyString( key ) ){
+  if( _.isEmpty( key ) || !_.isString( key) )  {
     throw new Error( 'invalid key, must be valid string' );
   }
   // key not set
@@ -65,7 +68,7 @@ VariableStore.prototype.isset = function( key ){
   delete a variable by key
 **/
 VariableStore.prototype.unset = function( key ){
-  if( !check.nonEmptyString( key ) ){
+  if( _.isEmpty( key ) || !_.isString( key) )  {
     throw new Error( 'invalid key, must be valid string' );
   }
   // key not set
@@ -81,7 +84,7 @@ VariableStore.prototype.unset = function( key ){
   import variables from a plain-old-javascript-object
 **/
 VariableStore.prototype.set = function( pojo ){
-  if( !check.object( pojo ) ){
+  if( !_.isPlainObject( pojo ) ){
     throw new Error( 'invalid object' );
   }
   for( var attr in pojo ){

package.json

@@ -24,7 +24,6 @@
   },
   "homepage": "https://github.com/pelias/query#readme",
   "dependencies": {
-    "check-types": "^8.0.0",
     "lodash": "^4.17.14"
   },
   "devDependencies": {