diff --git a/lib/event.js b/lib/event.js
index d664fe846..208c6c047 100644
--- a/lib/event.js
+++ b/lib/event.js
@@ -131,7 +131,7 @@ module.exports = {
 
   /**
    * @param {string} event
-   * @param {*} param
+   * @param {*} [param]
    */
   emit(event, param) {
     let msg = `Emitted | ${event}`;
diff --git a/lib/locator.js b/lib/locator.js
index f092f635a..0d7165fb7 100644
--- a/lib/locator.js
+++ b/lib/locator.js
@@ -7,14 +7,19 @@ const locatorTypes = ['css', 'by', 'xpath', 'id', 'name', 'fuzzy', 'frame', 'sha
 /** @class */
 class Locator {
   /**
-   * @param {CodeceptJS.LocatorOrString}  locator
-   * @param {string}  [defaultType]
+   * @param {CodeceptJS.LocatorOrString} locator
+   * @param {string} [defaultType]
    */
   constructor(locator, defaultType = '') {
     this.type = null;
     if (!locator) return;
 
     this.output = null;
+
+    /**
+     * @private
+     * @type {boolean}
+     */
     this.strict = false;
 
     if (typeof locator === 'object') {
@@ -76,61 +81,89 @@ class Locator {
   }
 
   /**
-   * @return  {string}
+   * @returns {string}
    */
   toString() {
     return this.output || `{${this.type}: ${this.value}}`;
   }
 
+  /**
+   * @returns {boolean}
+   */
   isFuzzy() {
     return this.type === 'fuzzy';
   }
 
+  /**
+   * @returns {boolean}
+   */
   isShadow() {
     return this.type === 'shadow';
   }
 
+  /**
+   * @returns {boolean}
+   */
   isFrame() {
     return this.type === 'frame';
   }
 
+  /**
+   * @returns {boolean}
+   */
   isCSS() {
     return this.type === 'css';
   }
 
+  /**
+   * @returns {boolean}
+   */
   isNull() {
     return this.type === null;
   }
 
+  /**
+   * @returns {boolean}
+   */
   isXPath() {
     return this.type === 'xpath';
   }
 
+  /**
+   * @returns {boolean}
+   */
   isCustom() {
-    return this.type && !locatorTypes.includes(this.type);
+    return !!this.type && !locatorTypes.includes(this.type);
   }
 
+  /**
+   * @returns {boolean}
+   */
   isStrict() {
     return this.strict;
   }
 
+  /**
+   * @returns {boolean}
+   */
   isAccessibilityId() {
     return this.isFuzzy() && this.value[0] === '~';
   }
 
   /**
-   * @return  {string}
+   * @returns {string}
    */
   toXPath() {
     if (this.isXPath()) return this.value;
     if (this.isCSS()) return cssToXPath(this.value);
+
     throw new Error('Can\'t be converted to XPath');
   }
 
   // DSL
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   or(locator) {
     const xpath = xpathLocator.combine([
@@ -142,7 +175,7 @@ class Locator {
 
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   find(locator) {
     const xpath = sprintf('%s//%s', this.toXPath(), convertToSubSelector(locator));
@@ -151,7 +184,7 @@ class Locator {
 
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   withChild(locator) {
     const xpath = sprintf('%s[./child::%s]', this.toXPath(), convertToSubSelector(locator));
@@ -160,7 +193,7 @@ class Locator {
 
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   withDescendant(locator) {
     const xpath = sprintf('%s[./descendant::%s]', this.toXPath(), convertToSubSelector(locator));
@@ -168,31 +201,35 @@ class Locator {
   }
 
   /**
-   * @param {number}  position
-   * @return {Locator}
+   * @param {number} position
+   * @returns {Locator}
    */
   at(position) {
-    if (position < 0) {
-      position++; // -1 points to the last element
-      // @ts-ignore
-      position = `last()-${Math.abs(position)}`;
-    }
     if (position === 0) {
       throw new Error('0 is not valid element position. XPath expects first element to have index 1');
     }
-    const xpath = sprintf('(%s)[position()=%s]', this.toXPath(), position);
+
+    let xpathPosition;
+
+    if (position > 0) {
+      xpathPosition = position.toString();
+    } else {
+      // -1 points to the last element
+      xpathPosition = `last()-${Math.abs(position + 1)}`;
+    }
+    const xpath = sprintf('(%s)[position()=%s]', this.toXPath(), xpathPosition);
     return new Locator({ xpath });
   }
 
   /**
-   * @return  {Locator}
+   * @returns {Locator}
    */
   first() {
     return this.at(1);
   }
 
   /**
-   * @return  {Locator}
+   * @returns {Locator}
    */
   last() {
     return this.at(-1);
@@ -200,7 +237,7 @@ class Locator {
 
   /**
    * @param {string} text
-   * @return  {Locator}
+   * @returns {Locator}
    */
   withText(text) {
     text = xpathLocator.literal(text);
@@ -209,13 +246,13 @@ class Locator {
   }
 
   /**
-   * @param {Object.<string, string>} attrs
-   * @return  {Locator}
+   * @param {Object.<string, string>} attributes
+   * @returns {Locator}
    */
-  withAttr(attrs) {
+  withAttr(attributes) {
     const operands = [];
-    for (const attr of Object.keys(attrs)) {
-      operands.push(`@${attr} = ${xpathLocator.literal(attrs[attr])}`);
+    for (const attr of Object.keys(attributes)) {
+      operands.push(`@${attr} = ${xpathLocator.literal(attributes[attr])}`);
     }
     const xpath = sprintf('%s[%s]', this.toXPath(), operands.join(' and '));
     return new Locator({ xpath });
@@ -223,7 +260,7 @@ class Locator {
 
   /**
    * @param {string} output
-   * @return  {Locator}
+   * @returns {Locator}
    */
   as(output) {
     this.output = output;
@@ -232,7 +269,7 @@ class Locator {
 
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   inside(locator) {
     const xpath = sprintf('%s[ancestor::%s]', this.toXPath(), convertToSubSelector(locator));
@@ -241,7 +278,7 @@ class Locator {
 
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   after(locator) {
     const xpath = sprintf('%s[preceding-sibling::%s]', this.toXPath(), convertToSubSelector(locator));
@@ -250,7 +287,7 @@ class Locator {
 
   /**
    * @param {CodeceptJS.LocatorOrString} locator
-   * @return  {Locator}
+   * @returns {Locator}
    */
   before(locator) {
     const xpath = sprintf('%s[following-sibling::%s]', this.toXPath(), convertToSubSelector(locator));
@@ -267,11 +304,21 @@ Locator.build = (locator) => {
   return new Locator(locator, 'css');
 };
 
+/**
+ * Filters to modify locators
+ */
 Locator.filters = [];
 
+/**
+ * Appends new `Locator` filter to an `Locator.filters` array, and returns the new length of the array.
+ */
 Locator.addFilter = fn => Locator.filters.push(fn);
 
 Locator.clickable = {
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   narrow: literal => xpathLocator.combine([
     `.//a[normalize-space(.)=${literal}]`,
     `.//button[normalize-space(.)=${literal}]`,
@@ -279,6 +326,10 @@ Locator.clickable = {
     `.//input[./@type = 'submit' or ./@type = 'image' or ./@type = 'button'][normalize-space(@value)=${literal}]`,
   ]),
 
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   wide: literal => xpathLocator.combine([
     `.//a[./@href][((contains(normalize-space(string(.)), ${literal})) or .//img[contains(./@alt, ${literal})])]`,
     `.//input[./@type = 'submit' or ./@type = 'image' or ./@type = 'button'][contains(./@value, ${literal})]`,
@@ -292,14 +343,27 @@ Locator.clickable = {
     `.//*[@aria-labelledby = //*[@id][normalize-space(string(.)) = ${literal}]/@id ]`,
   ]),
 
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   self: literal => `./self::*[contains(normalize-space(string(.)), ${literal}) or contains(normalize-space(@value), ${literal})]`,
 };
 
 Locator.field = {
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   labelEquals: literal => xpathLocator.combine([
     `.//*[self::input | self::textarea | self::select][not(./@type = 'submit' or ./@type = 'image' or ./@type = 'hidden')][((./@name = ${literal}) or ./@id = //label[@for][normalize-space(string(.)) = ${literal}]/@for or ./@placeholder = ${literal})]`,
     `.//label[normalize-space(string(.)) = ${literal}]//.//*[self::input | self::textarea | self::select][not(./@type = 'submit' or ./@type = 'image' or ./@type = 'hidden')]`,
   ]),
+
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   labelContains: literal => xpathLocator.combine([
     `.//*[self::input | self::textarea | self::select][not(./@type = 'submit' or ./@type = 'image' or ./@type = 'hidden')][(((./@name = ${literal}) or ./@id = //label[@for][contains(normalize-space(string(.)), ${literal})]/@for) or ./@placeholder = ${literal})]`,
     `.//label[contains(normalize-space(string(.)), ${literal})]//.//*[self::input | self::textarea | self::select][not(./@type = 'submit' or ./@type = 'image' or ./@type = 'hidden')]`,
@@ -307,7 +371,17 @@ Locator.field = {
     `.//*[@title = ${literal}]`,
     `.//*[@aria-labelledby = //*[@id][normalize-space(string(.)) = ${literal}]/@id ]`,
   ]),
+
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   byName: literal => `.//*[self::input | self::textarea | self::select][@name = ${literal}]`,
+
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   byText: literal => xpathLocator.combine([
     `.//*[self::input | self::textarea | self::select][not(./@type = 'submit' or ./@type = 'image' or ./@type = 'hidden')][(((./@name = ${literal}) or ./@id = //label[@for][contains(normalize-space(string(.)), ${literal})]/@for) or ./@placeholder = ${literal})]`,
     `.//label[contains(normalize-space(string(.)), ${literal})]//.//*[self::input | self::textarea | self::select][not(./@type = 'submit' or ./@type = 'image' or ./@type = 'hidden')]`,
@@ -316,52 +390,111 @@ Locator.field = {
 };
 
 Locator.checkable = {
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   byText: literal => xpathLocator.combine([
     `.//input[@type = 'checkbox' or @type = 'radio'][(@id = //label[@for][contains(normalize-space(string(.)), ${literal})]/@for) or @placeholder = ${literal}]`,
     `.//label[contains(normalize-space(string(.)), ${literal})]//input[@type = 'radio' or @type = 'checkbox']`,
   ]),
 
+  /**
+   * @param {string} literal
+   * @returns {string}
+   */
   byName: literal => `.//input[@type = 'checkbox' or @type = 'radio'][@name = ${literal}]`,
 };
 
 Locator.select = {
+  /**
+   * @param {string} opt
+   * @returns {string}
+   */
   byVisibleText: (opt) => {
     const normalized = `[normalize-space(.) = ${opt.trim()}]`;
     return `./option${normalized}|./optgroup/option${normalized}`;
   },
 
+  /**
+   * @param {string} opt
+   * @returns {string}
+   */
   byValue: (opt) => {
     const normalized = `[normalize-space(@value) = ${opt.trim()}]`;
     return `./option${normalized}|./optgroup/option${normalized}`;
   },
-
 };
 
 module.exports = Locator;
 
+/**
+ * @private
+ * Checks if `locator` is CSS locator
+ * @param {string} locator
+ *
+ * @returns {boolean}
+ */
 function isCSS(locator) {
   return locator[0] === '#' || locator[0] === '.' || locator[0] === '[';
 }
 
+/**
+ * @private
+ * Checks if `locator` is XPath locator
+ * @param {string} locator
+ *
+ * @returns {boolean}
+ */
 function isXPath(locator) {
   const trimmed = locator.replace(/^\(+/, '').substr(0, 2);
   return trimmed === '//' || trimmed === './';
 }
 
+/**
+ * @private
+ * **Experimental!** Works for WebDriver helper only
+ *
+ * Checks if `locator` is shadow locator.
+ *
+ * Shadow locators are
+ * `{ shadow: ['my-app', 'recipe-hello', 'button'] }`
+ *
+ * @param {{shadow: string[]}} locator
+ *
+ * @returns {boolean}
+ */
 function isShadow(locator) {
   const hasShadowProperty = (locator.shadow !== undefined) && (Object.keys(locator).length === 1);
   return hasShadowProperty;
 }
 
-function isXPathStartingWithRoundBrackets(locator) {
-  return isXPath(locator) && locator[0] === '(';
+/**
+ * @private
+ * Checks if xpath starts with `(`
+ * @param {string} xpath
+ * @returns {boolean}
+ */
+function isXPathStartingWithRoundBrackets(xpath) {
+  return isXPath(xpath) && xpath[0] === '(';
 }
 
+/**
+ * @private
+ * Removes `./` and `.//` symbols from xpath's start
+ * @param {string} xpath
+ * @returns {string}
+ */
 function removePrefix(xpath) {
   return xpath
     .replace(/^(\.|\/)+/, '');
 }
 
+/**
+ * @private
+ * @param {CodeceptJS.LocatorOrString} locator
+ * @returns {string}
+ */
 function convertToSubSelector(locator) {
   const xpath = (new Locator(locator, 'css')).toXPath();
   if (isXPathStartingWithRoundBrackets(xpath)) {
diff --git a/lib/output.js b/lib/output.js
index 42df19b1c..1c220f305 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -28,8 +28,8 @@ module.exports = {
 
   /**
    * Set or return current verbosity level
-   * @param {number} level
-   * @return {number}
+   * @param {number} [level]
+   * @returns {number}
    */
   level(level) {
     if (level !== undefined) outputLevel = level;
@@ -40,7 +40,7 @@ module.exports = {
    * Print information for a process
    * Used in multiple-run
    * @param {string} process
-   * @return {string}
+   * @returns {string}
    */
   process(process) {
     if (process === null) return outputProcess = '';
@@ -63,7 +63,9 @@ module.exports = {
    * @param {string} msg
    */
   log(msg) {
-    if (outputLevel >= 3) print(' '.repeat(this.stepShift), styles.log(truncate(`   ${msg}`, this.spaceShift)));
+    if (outputLevel >= 3) {
+      print(' '.repeat(this.stepShift), styles.log(truncate(`   ${msg}`, this.spaceShift)));
+    }
   },
 
   /**
@@ -83,11 +85,12 @@ module.exports = {
   },
 
   /**
-   * @param {string} name
+   * Prints plugin message
+   * @param {string} pluginName
    * @param {string} msg
    */
-  plugin(name, msg = '') {
-    this.debug(`<${name}> ${msg}`);
+  plugin(pluginName, msg = '') {
+    this.debug(`<${pluginName}> ${msg}`);
   },
 
   /**
diff --git a/lib/utils.js b/lib/utils.js
index d7edc35be..de20060ee 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -105,10 +105,20 @@ module.exports.template = function (template, data) {
   });
 };
 
+/**
+ * Make first char uppercase.
+ * @param {string} str
+ * @returns {string}
+ */
 module.exports.ucfirst = function (str) {
   return str.charAt(0).toUpperCase() + str.substr(1);
 };
 
+/**
+ * Make first char lowercase.
+ * @param {string} str
+ * @returns {string}
+ */
 module.exports.lcfirst = function (str) {
   return str.charAt(0).toLowerCase() + str.substr(1);
 };
@@ -148,6 +158,10 @@ module.exports.decodeUrl = function (url) {
 };
 
 module.exports.xpathLocator = {
+  /**
+   * @param {string} string
+   * @returns {string}
+   */
   literal: (string) => {
     if (string.indexOf("'") > -1) {
       string = string.split("'", -1).map(substr => `'${substr}'`).join(',"\'",');
@@ -155,6 +169,12 @@ module.exports.xpathLocator = {
     }
     return `'${string}'`;
   },
+
+  /**
+   * Combines passed locators into one disjunction one.
+   * @param {string[]} locators
+   * @returns {string}
+   */
   combine: locators => locators.join(' | '),
 };
 
@@ -378,6 +398,11 @@ function normalizeKeyReplacer(match, prefix, key, suffix, offset, string) {
   return normalizedKey + position.charAt(0).toUpperCase() + position.substr(1).toLowerCase();
 }
 
+/**
+ * Transforms `key` into normalized to OS key.
+ * @param {string} key
+ * @returns {string}
+ */
 module.exports.getNormalizedKeyAttributeValue = function (key) {
   // Use operation modifier key based on operating system
   key = key.replace(/(Ctrl|Control|Cmd|Command)[ _]?Or[ _]?(Ctrl|Control|Cmd|Command)/i, os.platform() === 'darwin' ? 'Meta' : 'Control');
diff --git a/package.json b/package.json
index 75670eeae..01b3a4488 100644
--- a/package.json
+++ b/package.json
@@ -60,13 +60,13 @@
     "allure-js-commons": "^1.3.2",
     "arrify": "^2.0.1",
     "axios": "^0.19.1",
-    "chalk": "^1.1.3",
+    "chalk": "^4.1.0",
     "commander": "^2.20.3",
     "css-to-xpath": "^0.1.0",
     "cucumber-expressions": "^6.6.2",
     "envinfo": "^7.5.1",
     "escape-string-regexp": "^1.0.3",
-    "figures": "^2.0.0",
+    "figures": "^3.2.0",
     "fn-args": "^4.0.0",
     "fs-extra": "^8.1.0",
     "gherkin": "^5.1.0",