diff --git a/.eslintrc.json b/.eslintrc.json
new file mode 100644
index 0000000..001aa19
--- /dev/null
+++ b/.eslintrc.json
@@ -0,0 +1,120 @@
+{
+	"parserOptions": {
+		"ecmaVersion": 6
+	},
+	"rules": {
+		"quotes": [
+			2,
+			"single",
+			{
+				"allowTemplateLiterals": true
+			}
+		],
+		"curly": [
+			2,
+			"all"
+		],
+		"keyword-spacing": [
+			2,
+			{
+				"overrides": {
+					"else": {
+						"before": true
+					},
+					"catch": {
+						"before": true,
+						"after": false
+					}
+				}
+			}
+		],
+		"space-before-blocks": [
+			2,
+			"always"
+		],
+		"wrap-iife": [
+			2,
+			"inside"
+		],
+		"space-before-function-paren": [
+			2,
+			"never"
+		],
+		"one-var": [
+			2,
+			"never"
+		],
+		"vars-on-top": 0,
+		"no-empty": [
+			2,
+			{
+				"allowEmptyCatch": true
+			}
+		],
+		"array-bracket-spacing": [
+			2,
+			"never"
+		],
+		"space-in-parens": [
+			2,
+			"never"
+		],
+		"no-underscore-dangle": 0,
+		"comma-style": [
+			2,
+			"last"
+		],
+		"comma-spacing": [
+			2,
+			{
+				"before": false,
+				"after": true
+			}
+		],
+		"space-unary-ops": [
+			2,
+			{
+				"words": false,
+				"nonwords": false
+			}
+		],
+		"no-multi-spaces": 2,
+		"space-infix-ops": 2,
+		"no-with": 2,
+		"indent": [
+			2,
+			"tab",
+			{
+				"SwitchCase": 1,
+				"FunctionExpression": {
+					"body": 1,
+					"parameters": 1
+				},
+				"MemberExpression": 0
+			}
+		],
+		"no-mixed-spaces-and-tabs": 2,
+		"no-trailing-spaces": 2,
+		"comma-dangle": [
+			2,
+			"never"
+		],
+		"semi": [2, "always"],
+		"brace-style": [
+			2,
+			"1tbs",
+			{
+				"allowSingleLine": true
+			}
+		],
+		"eol-last": 2,
+		"dot-notation": 0,
+		"no-multi-str": 2,
+		"key-spacing": [
+			2,
+			{
+				"afterColon": true
+			}
+		]
+	}
+}
diff --git a/src/popup/pwgen.css b/src/popup/pwgen.css
index 718675f..d520448 100644
--- a/src/popup/pwgen.css
+++ b/src/popup/pwgen.css
@@ -1,74 +1,74 @@
 body {
-  margin: 15px;
+	margin: 15px;
 }
 
 div {
-  margin-top: 5px;
+	margin-top: 5px;
 }
 
 input[type="number"] {
-  -moz-appearance: none;
-  color: var(--in-content-text-color);
-  border: 1px solid var(--in-content-box-border-color);
-  -moz-border-top-colors: none !important;
-  -moz-border-right-colors: none !important;
-  -moz-border-bottom-colors: none !important;
-  -moz-border-left-colors: none !important;
-  border-radius: 2px;
-  background-color: var(--in-content-box-background);
+	-moz-appearance: none;
+	color: var(--in-content-text-color);
+	border: 1px solid var(--in-content-box-border-color);
+	-moz-border-top-colors: none !important;
+	-moz-border-right-colors: none !important;
+	-moz-border-bottom-colors: none !important;
+	-moz-border-left-colors: none !important;
+	border-radius: 2px;
+	background-color: var(--in-content-box-background);
 
-  font-family: inherit;
-  font-size: inherit;
-  padding: 5px 10px;
+	font-family: inherit;
+	font-size: inherit;
+	padding: 5px 10px;
 
-  width: 50px;
+	width: 50px;
 }
 
 #length-min {
-  margin-right: 10px;
+	margin-right: 10px;
 }
 
 input[type="checkbox"] {
-  margin-bottom: -7px;
+	margin-bottom: -7px;
 }
 
 #pw {
-  border: 2px black solid;
-  width: 250px;
+	border: 2px black solid;
+	width: 250px;
 }
 
 #copy {
-  margin-left: 0px;
+	margin-left: 0px;
 }
 
 #exclude {
-  width: 183px;
+	width: 183px;
 }
 
 .copied {
-  pointer-events: none;
-  height: 26px;
-  width: 100%;
-  background-color: #FFF8DC;
-  position: absolute;
-  padding-right: 0;
-  padding-left: 0;
-  padding-top: 5px;
-  padding-bottom: 5px;
-  text-align: center;
-  margin-right: -15px;
-  margin-left: -19px;
-  margin-top: -27px;
+	pointer-events: none;
+	height: 26px;
+	width: 100%;
+	background-color: #FFF8DC;
+	position: absolute;
+	padding-right: 0;
+	padding-left: 0;
+	padding-top: 5px;
+	padding-bottom: 5px;
+	text-align: center;
+	margin-right: -15px;
+	margin-left: -19px;
+	margin-top: -27px;
 }
 
 .fadein {
-  visibility: visible;
-  opacity: 1;
-  transition: opacity 1s linear;
+	visibility: visible;
+	opacity: 1;
+	transition: opacity 1s linear;
 }
 
 .fadeout {
-  visibility: hidden;
-  opacity: 0;
-  transition: visibility 0s 1s, opacity 1s linear;
+	visibility: hidden;
+	opacity: 0;
+	transition: visibility 0s 1s, opacity 1s linear;
 }
diff --git a/src/popup/pwgen.html b/src/popup/pwgen.html
index e4d1e7e..04e0e50 100644
--- a/src/popup/pwgen.html
+++ b/src/popup/pwgen.html
@@ -1,50 +1,50 @@
 <!DOCTYPE html>
 <html>
-  <head>
-    <meta charset="utf-8">
-    <meta name="viewport" content="width=device-width, initial-scale=1">
-    <link rel="stylesheet" href="chrome://global/skin/global.css" type="text/css" />
-    <link rel="stylesheet" href="chrome://global/skin/in-content/common.css" type="text/css" />
+	<head>
+		<meta charset="utf-8">
+		<meta name="viewport" content="width=device-width, initial-scale=1">
+		<link rel="stylesheet" href="chrome://global/skin/global.css" type="text/css" />
+		<link rel="stylesheet" href="chrome://global/skin/in-content/common.css" type="text/css" />
 
-    <link rel="stylesheet" href="pwgen.css"/>
-  </head>
+		<link rel="stylesheet" href="pwgen.css"/>
+	</head>
 
 <body>
-  <form>
-    <div>
-      <input type="text" id="pw" name="pw">
-    </div>
+	<form>
+		<div>
+			<input type="text" id="pw" name="pw">
+		</div>
 
-    <div>
-      <label>Length: </label>
-      <label for="length-min">min.</label> <input type="number" id="length-min" value="14" min="0" name="length-min">
-      <label for="length-max">max.</label> <input type="number" id="length-max" value="18" min="0" name="length-max">
-    </div>
+		<div>
+			<label>Length: </label>
+			<label for="length-min">min.</label> <input type="number" id="length-min" value="14" min="0" name="length-min">
+			<label for="length-max">max.</label> <input type="number" id="length-max" value="18" min="0" name="length-max">
+		</div>
 
-    <div>
-      <input type="checkbox" id="special" checked="checked" name="special">
-      <label for="special">Include special characters</label>
-    </div>
+		<div>
+			<input type="checkbox" id="special" checked="checked" name="special">
+			<label for="special">Include special characters</label>
+		</div>
 
-    <div>
-      <label for="exclude">Exclude: </label>
-      <input type="text" id="exclude" name="exclude">
-    </div>
+		<div>
+			<label for="exclude">Exclude: </label>
+			<input type="text" id="exclude" name="exclude">
+		</div>
 
-    <div>
-      <button id="copy">Copy to clipboard</button><button id="new">Generate another</button>
-    </div>
+		<div>
+			<button id="copy">Copy to clipboard</button><button id="new">Generate another</button>
+		</div>
 
-    <hr>
+		<hr>
 
-    <div>
-      <input type="checkbox" id="directcopy" name="directcopy" title="The next time the toolbar button is clicked, the password is copied to the clipboard directly">
-      <label for="directcopy">Copy directly</label>
-      <div class="copied" style="display: none;">Password copied to clipboard</div>
-    </div>
+		<div>
+			<input type="checkbox" id="directcopy" name="directcopy" title="The next time the toolbar button is clicked, the password is copied to the clipboard directly">
+			<label for="directcopy">Copy directly</label>
+			<div class="copied" style="display: none;">Password copied to clipboard</div>
+		</div>
 
-  </form>
-  <script src="pwgen.js"></script>
+	</form>
+	<script src="pwgen.js"></script>
 </body>
 
 </html>
diff --git a/src/popup/pwgen.js b/src/popup/pwgen.js
index f052fbf..df2aac7 100644
--- a/src/popup/pwgen.js
+++ b/src/popup/pwgen.js
@@ -1,114 +1,113 @@
 function randPassword(length, includeSpecial, exclude) {
-  let pwdChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
-  if (includeSpecial) {
-    pwdChars += '!"#$%&\'()*+,-./:;<=>?@[\]^_`{|}~';
-  }
+	let pwdChars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
+	if (includeSpecial) {
+		pwdChars += '!"#$%&\'()*+,-./:;<=>?@[\]^_`{|}~';
+	}
 
-  if (exclude) {
-    exclude.split('').forEach(c => {
-      pwdChars = pwdChars.split(c).join('');
-    });
-  }
+	if (exclude) {
+		exclude.split('').forEach(c => {
+			pwdChars = pwdChars.split(c).join('');
+		});
+	}
 
-  let randValues = new Uint32Array(length);
-  let randPwd = '';
-  window.crypto.getRandomValues(randValues);
-  for(i=0; i<length; i++)
-  {
-    randPwd += pwdChars[randValues[i] % pwdChars.length];
-  }
-  return randPwd;
+	let randValues = new Uint32Array(length);
+	let randPwd = '';
+	window.crypto.getRandomValues(randValues);
+	for (i = 0; i < length; i++) {
+		randPwd += pwdChars[randValues[i] % pwdChars.length];
+	}
+	return randPwd;
 }
 
 function generateLength() {
-  return Math.floor(Math.random() * (getParams().lengthMax - getParams().lengthMin + 1) + getParams().lengthMin);
+	return Math.floor(Math.random() * (getParams().lengthMax - getParams().lengthMin + 1) + getParams().lengthMin);
 }
 
 function getParams() {
-  return {
-    lengthMin: parseInt(document.getElementById('length-min').value),
-    lengthMax: parseInt(document.getElementById('length-max').value),
-    special: document.getElementById('special').checked,
-    exclude: document.getElementById('exclude').value,
-    directcopy: document.getElementById('directcopy').checked
-  }
+	return {
+		lengthMin: parseInt(document.getElementById('length-min').value),
+		lengthMax: parseInt(document.getElementById('length-max').value),
+		special: document.getElementById('special').checked,
+		exclude: document.getElementById('exclude').value,
+		directcopy: document.getElementById('directcopy').checked
+	};
 }
 
 function loadOptions() {
-  return browser.storage.local.get({
-    lengthMin: 14,
-    lengthMax: 17,
-    special: true,
-    exclude: 'iIl|10o8B3Evu![]{}',
-    directcopy: false
-  });
+	return browser.storage.local.get({
+		lengthMin: 14,
+		lengthMax: 17,
+		special: true,
+		exclude: 'iIl|10o8B3Evu![]{}',
+		directcopy: false
+	});
 }
 
 function saveOptions(options) {
-  return browser.storage.local.set(options);
+	return browser.storage.local.set(options);
 }
 
 function copypasstoclippboard(cb) {
-  setTimeout(function() {
-    var copyText = document.getElementById('pw');
-    copyText.select();
-    document.execCommand('copy');
-    if (typeof(cb) === 'function') {
-      cb();
-    }
-    fade(document.getElementsByClassName('copied')[0]);
-  }, 200);
+	setTimeout(function() {
+		var copyText = document.getElementById('pw');
+		copyText.select();
+		document.execCommand('copy');
+		if (typeof(cb) === 'function') {
+			cb();
+		}
+		fade(document.getElementsByClassName('copied')[0]);
+	}, 200);
 }
 
 function fade(element) {
-  var clone = element.cloneNode(true);
-  clone.style.display = 'block';
-  element.parentNode.insertBefore(clone, element.nextSibling);
+	var clone = element.cloneNode(true);
+	clone.style.display = 'block';
+	element.parentNode.insertBefore(clone, element.nextSibling);
 
-  setTimeout(() => {
-    clone.className += ' fadeout';
-  }, 500);
+	setTimeout(() => {
+		clone.className += ' fadeout';
+	}, 500);
 
-  setTimeout(() => {
-    clone.remove();
-  }, 1600);
+	setTimeout(() => {
+		clone.remove();
+	}, 1600);
 }
 
 document.addEventListener('DOMContentLoaded', function() {
 
-  document.getElementById('new').addEventListener('click', (ev) => {
-    ev.preventDefault();
-    var params = getParams();
-    document.getElementById('pw').value = randPassword(generateLength(), params.special, params.exclude);
+	document.getElementById('new').addEventListener('click', (ev) => {
+		ev.preventDefault();
+		var params = getParams();
+		document.getElementById('pw').value = randPassword(generateLength(), params.special, params.exclude);
 
-    if (params.directcopy) {
-      copypasstoclippboard();
-    }
-  });
+		if (params.directcopy) {
+			copypasstoclippboard();
+		}
+	});
 
-  document.getElementById('copy').addEventListener('click', (ev) => {
-    ev.preventDefault();
-    copypasstoclippboard();
-  });
+	document.getElementById('copy').addEventListener('click', (ev) => {
+		ev.preventDefault();
+		copypasstoclippboard();
+	});
 
-  var list = document.getElementsByTagName('input');
-  for (var i = 0; i < list.length; i++) {
-    list[i].addEventListener('change', (ev) => {
-      saveOptions(getParams());
-    });
-  }
+	var list = document.getElementsByTagName('input');
+	for (var i = 0; i < list.length; i++) {
+		list[i].addEventListener('change', (ev) => {
+			saveOptions(getParams());
+		});
+	}
 
-  loadOptions().then((options) => {
-    document.getElementById('length-min').value = options.lengthMin;
-    document.getElementById('length-max').value = options.lengthMax;
-    document.getElementById('special').checked = options.special;
-    document.getElementById('exclude').value = options.exclude;
-    document.getElementById('directcopy').checked = options.directcopy;
-    document.getElementById('pw').value = randPassword(generateLength(), getParams().special, getParams().exclude);
+	loadOptions().then((options) => {
+		document.getElementById('length-min').value = options.lengthMin;
+		document.getElementById('length-max').value = options.lengthMax;
+		document.getElementById('special').checked = options.special;
+		document.getElementById('exclude').value = options.exclude;
+		document.getElementById('directcopy').checked = options.directcopy;
+		document.getElementById('pw').value = randPassword(generateLength(), getParams().special, getParams().exclude);
 
-    if (options.directcopy) {
-      copypasstoclippboard();
-    }
-  });
+		if (options.directcopy) {
+			copypasstoclippboard();
+		}
+	});
 
 });