JavaScript Reference

Method/Property Description Example
console.log() Outputs a message to the console console.log('Hello');
alert() Displays an alert dialog alert('Hello');
document.getElementById() Gets an element by its ID document.getElementById('demo');
document.querySelector() Selects the first element matching a CSS selector document.querySelector('.class');
addEventListener() Attaches an event listener to an element element.addEventListener('click', function);
innerHTML Gets or sets the HTML content element.innerHTML = 'New content';
textContent Gets or sets the text content element.textContent = 'New text';
Array.length Returns the length of an array arr.length;
Array.push() Adds elements to the end of an array arr.push('item');
Array.pop() Removes the last element from an array arr.pop();
String.length Returns the length of a string str.length;
String.toUpperCase() Converts a string to uppercase str.toUpperCase();