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Question 45 of 50easy

What are useful Console methods?

Understanding console debugging techniques.

What You'll Learn

  • Beyond console.log
  • Formatting output
  • Performance measurement

Basic Methods

code.jsJavaScript
console.log('Regular log');
console.info('Information');
console.warn('Warning');
console.error('Error');
console.debug('Debug info');

Formatting

code.jsJavaScript
// String substitution
console.log('Hello, %s!', 'World');
console.log('Count: %d', 42);
console.log('Object: %o', { a: 1 });

// CSS styling
console.log(
  '%cStyled text',
  'color: blue; font-size: 20px; font-weight: bold;'
);

Tables and Groups

code.jsJavaScript
// Table
const users = [
  { name: 'John', age: 30 },
  { name: 'Jane', age: 25 }
];
console.table(users);

// Groups
console.group('User Details');
console.log('Name: John');
console.log('Age: 30');
console.groupEnd();

// Collapsed group
console.groupCollapsed('More Info');
console.log('...');
console.groupEnd();

Timing and Counting

code.jsJavaScript
// Timing
console.time('operation');
// ... code ...
console.timeEnd('operation');
// operation: 123.456ms

// Counting
for (let i = 0; i < 5; i++) {
  console.count('loop');
}
// loop: 1, loop: 2, ...
console.countReset('loop');

Other Useful Methods

code.jsJavaScript
// Clear console
console.clear();

// Assert (logs only if false)
console.assert(1 === 2, 'Math is broken!');

// Stack trace
console.trace('Where am I?');

// Directory (object properties)
console.dir(document.body);