Widget
// Definition
A self-contained, reusable UI component — date picker, rich-text editor, file uploader, chart, or similar — embedded in a page or third-party surface. Testing a widget involves verifying its own behaviour (correct state transitions, keyboard accessibility, error states), its integration with the host form or page (does it emit the right value on change?), and edge cases specific to its type (date picker: leap years, min/max constraints; file uploader: MIME type and size limits). Third-party embedded widgets also require cross-origin and content-security-policy testing.
// Related terms
Data Visualization
Charts, graphs, maps, and dashboards that render data graphically. Testing concerns span correctness (does the chart reflect the underlying data accurately, including edge cases like empty datasets, single data points, and very large values?), accessibility (colour-blind-safe palettes, ARIA labels on SVG elements, keyboard navigation), and rendering consistency across screen sizes and browsers. Snapshot or pixel-diff testing can catch visual regressions in chart rendering.
DOM
The Document Object Model — a tree-shaped, in-memory representation of an HTML (or XML) document that the browser builds after parsing the page source. Each element becomes a node, and JavaScript (and test tools like Playwright and Selenium) interact with the page by traversing and manipulating this tree. Understanding the DOM is essential for writing stable locators: a query like `#submit-btn` targets the DOM node, not the raw HTML string.