JavaScript String

// String Literals (Primitives)
const singleQuotes = 'literal';
const doubleQuotes = "literal";
const templateLiteral = `literal`; // Supports expression interpolation: `${var}`

// Type Coercion (Primitive)
const coercedString = String(100n); // "100"

// String Object (Wrapper Object)
const stringObject = new String("object"); 
typeof singleQuotes; // "string"
typeof stringObject; // "object"

let str = "Byte";
str[0] = "b"; // Fails silently (or throws TypeError in strict mode)
console.log(str); // "Byte"

str = "byte"; // Reassignment of the variable, not modification of the original string

const bmpChar = "A";
console.log(bmpChar.length); // 1

const astralChar = "🚀";
console.log(astralChar.length); // 2 (High and low surrogate code units)

const primitive = "data";
// JS engine internally executes: new String("data").toUpperCase()
const upper = primitive.toUpperCase(); 

const str = "Node";

// Bracket notation (returns undefined if out of bounds)
str[0]; // "N"

// charAt() method (returns empty string if out of bounds)
str.charAt(1); // "o"

// at() method (supports negative integers for reverse indexing)
str.at(-1); // "e"

const str = "JavaScript";
str.slice(0, 4);      // "Java" (Extracts from start index to end index)
str.substring(4, 10); // "Script" (Similar to slice, but swaps indices if start > end)

const str = "Runtime";
str.indexOf("time");    // 3 (Returns starting index, or -1 if not found)
str.includes("Run");    // true (Returns boolean)
str.startsWith("Run");  // true
str.endsWith("me");     // true
str.match(/[a-z]+/g);   // ["untime"] (Executes regex search, returns array of matches)

const str = "  Parse  ";
str.trim();                  // "Parse" (Removes leading/trailing whitespace)
str.replace("P", "p");       // "  parse  " (Replaces first match)
str.replaceAll(/\s/g, "");   // "Parse" (Replaces all matches)
str.toLowerCase();           // "  parse  "
str.toUpperCase();           // "  PARSE  "
str.concat(" Tree");         // "  Parse   Tree"

const str = "a,b,c";
str.split(","); // ["a", "b", "c"] (Splits string into an array based on a delimiter)