Day 5 of 100: Loops — Data-Driven Tests and Retry Logic

Day 5 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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Loops drive data-driven tests, retries, and bulk validations.

The Loops That Matter

const browsers = ['chromium', 'firefox', 'webkit'];

// for...of — the workhorse for test data
for (const browser of browsers) {
  console.log('Testing on ' + browser);
}

// Classic for — when you need the index
for (let i = 0; i < browsers.length; i++) {
  console.log(i + ': ' + browsers[i]);
}

// while — retry pattern
let attempts = 0;
let success = false;
while (!success && attempts < 3) {
  attempts++;
  success = attempts === 2; // simulate pass on 2nd try
}

Data-Driven Test Pattern (Preview)

const loginCases = [
  { email: 'valid@test.com', pass: 'ok123', expect: 'dashboard' },
  { email: 'bad@test.com', pass: 'wrong', expect: 'error' },
  { email: '', pass: 'ok123', expect: 'error' },
];

for (const tc of loginCases) {
  console.log('Case: ' + tc.email + ' expects ' + tc.expect);
  // In Playwright this becomes: test('login ' + tc.email, ...)
}

break and continue

for (const tc of loginCases) {
  if (tc.skip) continue;       // skip marked cases
  if (tc.critical && failed) break; // stop on critical failure
}

Tomorrow (Day 6): Functions — reusable test helpers.