Day 6 of 100: Functions — Building Reusable Test Helpers

Day 6 of 100 — 100 Days of Playwright with TypeScript Challenge. Phase: JavaScript Fundamentals. JavaScript (Days 1-33) → TypeScript (Days 34-63) → Playwright (Days 64-96) → AI Framework Capstone (Days 97-100).

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Functions turn repeated test steps into reusable helpers. The foundation of every utility file.

Declaring Functions

// Function declaration — hoisted
function buildUrl(path) {
  return 'https://api.example.com' + path;
}

// Function expression
const validate = function(status) {
  return status >= 200 && status < 300;
};

console.log(buildUrl('/users'));  // https://api.example.com/users
console.log(validate(201));        // true

Parameters and Defaults

function createUser(name, role = 'viewer', active = true) {
  return { name, role, active };
}

createUser('Jane');                  // role defaults to viewer
createUser('Admin', 'admin', false); // all explicit

Return Early, Return Often

function getTestEnv(name) {
  if (name === 'prod') return 'https://example.com';
  if (name === 'staging') return 'https://staging.example.com';
  return 'http://localhost:3000';
}

Tomorrow (Day 7): Arrow functions — the syntax Playwright uses everywhere.