Added JavaScript sheet.

README.md

@@ -1,6 +1,8 @@
 # CheetSheetz
 
-Collection of various technical "cheat sheets".
+## Personal composition of various technical "cheat sheets".
+
+[JavaScript](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/javascript.md)
 
 [Markdown](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/markdown.md)
 

javascript.md

@@ -0,0 +1,248 @@
+# JavaScript Cheat Sheet
+
+## Table of Contents
+
+1. [Variables](#variables)
+2. [Data Types](#data-types)
+3. [Operators](#operators)
+4. [Control Structures](#control-structures)
+5. [Functions](#functions)
+6. [Arrays](#arrays)
+7. [Strings](#strings)
+8. [Objects](#objects)
+9. [DOM Manipulation](#dom-manipulation)
+10. [Asynchronous JavaScript](#asynchronous-javascript)
+11. [Error Handling](#error-handling)
+
+## Variables
+
+### Declaration and Assignment
+```javascript
+let variableName = value;
+```
+
+### Variable Types
+- String: `let stringVariable = "Hello";`
+- Number: `let numberVariable = 42;`
+- Boolean: `let boolVariable = true;`
+- Undefined: `let undefinedVariable;`
+- Null: `let nullVariable = null;`
+
+## Data Types
+
+### Primitive Types
+- String
+- Number
+- Boolean
+- Undefined
+- Null
+
+### Reference Types
+- Object
+- Array
+- Function
+
+## Operators
+
+### Arithmetic Operators
+```javascript
++, -, *, /, %, ++, --
+```
+
+### Comparison Operators
+```javascript
+==, ===, !=, !==, <, >, <=, >=
+```
+
+### Logical Operators
+```javascript
+&& (and), || (or), ! (not)
+```
+
+### Assignment Operators
+```javascript
+=, +=, -=, *=, /=, %=
+```
+
+## Control Structures
+
+### If Statement
+```javascript
+if (condition) {
+    // code to be executed if the condition is true
+} else if (anotherCondition) {
+    // code to be executed if the previous condition was false and this one is true
+} else {
+    // code to be executed if all conditions are false
+}
+```
+
+### Switch Statement
+```javascript
+switch (variable) {
+    case value1:
+        // code to be executed if variable equals value1
+        break;
+    case value2:
+        // code to be executed if variable equals value2
+        break;
+    default:
+        // code to be executed if variable doesn't match any case
+}
+```
+
+### Loops
+#### For Loop
+```javascript
+for (let i = 0; i < 5; i++) {
+    // code to be executed in each iteration
+}
+```
+
+#### While Loop
+```javascript
+while (condition) {
+    // code to be executed as long as the condition is true
+}
+```
+
+#### Do-While Loop
+```javascript
+do {
+    // code to be executed at least once, then repeated as long as the condition is true
+} while (condition);
+```
+
+## Functions
+
+### Function Declaration
+```javascript
+function functionName(param1, param2) {
+    // code to be executed
+    return result; // optional
+}
+```
+
+### Arrow Functions
+```javascript
+const add = (a, b) => a + b;
+```
+
+### Function Call
+```javascript
+let result = functionName(arg1, arg2);
+```
+
+## Arrays
+
+### Array Declaration
+```javascript
+let arrayName = [value1, value2, value3];
+```
+
+### Array Methods
+```javascript
+arrayName.push(newValue); // Add to the end
+arrayName.pop(); // Remove from the end
+arrayName.unshift(newValue); // Add to the beginning
+arrayName.shift(); // Remove from the beginning
+```
+
+## Strings
+
+### Template Literals
+```javascript
+let name = "World";
+let greeting = `Hello, ${name}!`;
+```
+
+### String Methods
+```javascript
+let str = "Hello, World!";
+str.length; // Length of the string
+str.indexOf("World"); // Index of the first occurrence of "World"
+str.slice(start, end); // Extract a portion of the string
+```
+
+## Objects
+
+### Object Declaration
+```javascript
+let person = {
+    name: "John",
+    age: 30,
+    isStudent: false
+};
+```
+
+### Object Methods
+```javascript
+person.sayHello = function() {
+    console.log(`Hello, my name is ${this.name}.`);
+};
+```
+
+## DOM Manipulation
+
+### Selecting Elements
+```javascript
+let elementById = document.getElementById("elementId");
+let elementByClass = document.getElementsByClassName("className");
+let elementByTag = document.getElementsByTagName("tagName");
+```
+
+### Modifying Elements
+```javascript
+elementById.innerHTML = "New content";
+elementById.style.color = "red";
+```
+
+## Asynchronous JavaScript
+
+### Callbacks
+```javascript
+function fetchData(callback) {
+    // asynchronous operation
+    setTimeout(() => {
+        let data = "This is the data.";
+        callback(data);
+    }, 1000);
+}
+
+fetchData((result) => {
+    console.log(result);
+});
+```
+
+### Promises
+```javascript
+function fetchData() {
+    return new Promise((resolve, reject) => {
+        // asynchronous operation
+        setTimeout(() => {
+            let data = "This is the data.";
+            resolve(data);
+            // reject("Error occurred"); // Uncomment to simulate an error
+        }, 1000);
+    });
+}
+
+fetchData()
+    .then(result => console.log(result))
+    .catch(error => console.error(error));
+```
+
+## Error Handling
+
+### Try-Catch Block
+```javascript
+try {
+    // code that may throw an error
+} catch (error) {
+    // handle the error
+    console.error("Error: " + error.message);
+}
+```
+
+```
+