Added the isJsonString method to the json module.

README.md

@@ -76,6 +76,17 @@ flattenObject(obj);
 ```
 
 
+#### isJsonString(str)
+
+Returns a boolean that specifies whether the string is parsable JSON.
+
+```JavaScript
+const str = JSON.stringify({red: 5, green: 6});
+
+isJsonString(str); // true
+``` 
+
+
 #### stringToBoolean(str)
 
 Usually used for url parameters, converts null, undefined, 0, false, or '' to false even if they are strings. All other values are true.

lib/json.js

@@ -1,5 +1,13 @@
 const _ = require('lodash');
 
+function isJsonString(str) {
+  try {
+    return _.isObject(JSON.parse(str));
+  } catch (e) {
+    return false;
+  }
+}
+
 function safeJsonParse(obj) {
   if (obj && _.isString(obj)) {
     try {
@@ -12,5 +20,6 @@ function safeJsonParse(obj) {
 }
 
 module.exports = {
+  isJsonString,
   safeJsonParse
 };

test/json.spec.js

@@ -1,8 +1,42 @@
 const { expect } = require('chai');
 
-const { safeJsonParse } = require('../');
+const { isJsonString, safeJsonParse } = require('../');
+
+describe('json', function () {
+  describe('isJsonString()', function () {
+    it('should return false if passed undefined', function () {
+      expect(isJsonString(undefined)).to.be.false;
+    });
+
+    it('should return false if passed null', function () {
+      expect(isJsonString(null)).to.be.false;
+    });
+
+    it('should return false if passed a blank string', function () {
+      expect(isJsonString('')).to.be.false;
+    });
+
+    it('should return false if passed a number', function () {
+      expect(isJsonString(555)).to.be.false;
+    });
+
+    it('should return false if passed an invalid json object string', function () {
+      expect(isJsonString('{"red":5,"green":55,"blue":Koolaid"}')).to.be.false;
+    });
+
+    it('should return false if passed an invalid json array string', function () {
+      expect(isJsonString('["Red","Green","Blue"')).to.be.false;
+    });
+
+    it('should return true if passed a valid json object string', function () {
+      expect(isJsonString('{"red":5,"green":55,"blue":"Koolaid"}')).to.be.true;
+    });
+
+    it('should return true if passed a valid json array string', function () {
+      expect(isJsonString('["Red","Green","Blue"]')).to.be.true;
+    });
+  });
 
-describe('json', function() {
   describe('safeJsonParse()', function () {
     it('should return null if passed undefined', function () {
       expect(safeJsonParse(undefined)).to.be.null;