feat(loki): add simplified javascript comparisons $jgt, $jgte, $jlt, …

…$jlte, $jbetween (#87)

See techfort/LokiJS@bb011df

packages/loki/spec/generic/ops.spec.ts

@@ -373,6 +373,26 @@ describe("Individual operator tests", () => {
     expect(coll.chain().find({a: {$gte: "7.2"}}).find({a: {$finite: true}}).data().length).toEqual(3); // 7.2, "11", "18.1"
     expect(coll.find({a: {$gt: "7.2"}}).length).toEqual(3); // "11", "18.1", "asdf"
     expect(coll.find({a: {$lte: "7.2"}}).length).toEqual(7); // 7.2, "5", "4", 4, 2, 1, null
+  });
 
+  it("js range ops work as expected", () => {
+    const db = new Loki("db");
+    const coll = db.addCollection<{a: string | number, b:number}>("coll");
+
+    coll.insert({ a: null, b: 5});
+    coll.insert({ a: "11", b: 5});
+    coll.insert({ a: 2, b: 5});
+    coll.insert({ a: "1", b: 5});
+    coll.insert({ a: "4", b: 5});
+    coll.insert({ a: 7.2, b: 5});
+    coll.insert({ a: "5", b: 5});
+    coll.insert({ a: 4, b: 5});
+    coll.insert({ a: "18.1", b: 5});
+
+    expect(coll.find({ a: { $jgt: 5 } }).length).toEqual(3);
+    expect(coll.find({ a: { $jgte: 5 } }).length).toEqual(4);
+    expect(coll.find({ a: { $jlt: 7.2 } }).length).toEqual(6);
+    expect(coll.find({ a: { $jlte: 7.2 } }).length).toEqual(7);
+    expect(coll.find({ a: { $jbetween: [3.2, 7.8] } }).length).toEqual(4);
   });
 });

packages/loki/src/result_set.ts

@@ -111,6 +111,28 @@ export const LokiOps = {
     return (gtHelper(a, range[0], true) && ltHelper(a, range[1], true));
   },
 
+  // lightweight javascript comparisons
+  $jgt(a: any, b: any): boolean {
+    return a > b;
+  },
+
+  $jgte(a: any, b: any): boolean {
+    return a >= b;
+  },
+
+  $jlt(a: any, b: any): boolean {
+    return a < b;
+  },
+
+  $jlte(a: any, b: any): boolean {
+    return a <= b;
+  },
+
+  $jbetween(a: any, range: [any, any]): boolean {
+    if (a === undefined || a === null) return false;
+    return (a >= range[0] && a <= range[1]);
+  },
+
   $in(a: any, b: any): boolean {
     return b.indexOf(a) !== -1;
   },
@@ -1265,6 +1287,16 @@ export namespace ResultSet {
     $len?: number;
   } | {
     $where?: (val?: R) => boolean;
+  } | {
+    $jgt?: R;
+  } | {
+    $jgte?: R;
+  } | {
+    $jlt?: R;
+  } | {
+    $jlte?: R;
+  } | {
+    $jbetween?: [R, R];
   };
 
   export type Query<T> =