Return boolean values instead of "true"/"false" strings.

When boolean values are set in an .env file (e.g. IS_PRODUCTION=false), it's expected that these will be evalulated as booleans, instead of the string "false" (which is truthy).  This causes particular problems when using webpack and webpack.DefinePlugin, since providing `JSON.stringify(process.env.IS_PRODUCTION` will evaluate as a string, which is unexpected.

Instead, change `"true"` to `true` and `"false"` to `false` when evaluating the .env file.

README.md

@@ -67,7 +67,7 @@ _Alias: `load`_
 
 `config` will read your .env file, parse the contents, assign it to
 [`process.env`](https://nodejs.org/docs/latest/api/process.html#process_process_env),
-and return an Object with a `parsed` key containing the loaded content or an `error` key if it failed.  
+and return an Object with a `parsed` key containing the loaded content or an `error` key if it failed.
 
 ```js
 const result = dotenv.config()
@@ -135,6 +135,7 @@ line'}
 ```
 - inner quotes are maintained (think JSON) (`JSON={"foo": "bar"}` becomes `{JSON:"{\"foo\": \"bar\"}"`)
 - whitespace is removed from both ends of the value (see more on [`trim`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim)) (`FOO="  some value  "` becomes `{FOO: 'some value'}`)
+- booleans are maintained  (`TRUTHY_VALUE=true` becomes `{TRUTHY_VALUE: true}`)
 
 ## FAQ
 

lib/main.js

@@ -30,6 +30,13 @@ function parse (src) {
       // remove any surrounding quotes and extra spaces
       value = value.replace(/(^['"]|['"]$)/g, '').trim()
 
+      // set booleans appropriately instead of boolean strings
+      if (value === 'true') {
+        value = true
+      } else if (value === 'false') {
+        value = false
+      }
+
       obj[key] = value
     }
   })

test/.env

@@ -16,3 +16,5 @@ RETAIN_INNER_QUOTES={"foo": "bar"}
 RETAIN_INNER_QUOTES_AS_STRING='{"foo": "bar"}'
 INCLUDE_SPACE=some spaced out string
 USERNAME="therealnerdybeast@example.tld"
+FALSEY_VALUE=false
+TRUTHY_VALUE=true

test/main.js

@@ -179,5 +179,11 @@ describe('dotenv', function () {
       parsed.should.have.property('USERNAME', 'therealnerdybeast@example.tld')
       done()
     })
+
+    it('parses booleans correctly', function (done) {
+      parsed.should.have.property('FALSEY_VALUE', false)
+      parsed.should.have.property('TRUTHY_VALUE', true)
+      done()
+    })
   })
 })