Util

Util is maptalks' collection of general utility functions (located in core/util/util.ts), providing animation frames, image loading, coordinate iteration, math interpolation, and string/encoding conversions. It is a static function collection that is never instantiated; import it with import { Util } from "maptalks".

import { Util } from "maptalks";

const id = Util.UID();
console.log(Util.clamp(10, 0, 5)); // 5

Main Functions

• requestAnimFrame(callback): number — Request an animation frame (falls back to setTimeout(cb, 16) in Node).
• cancelAnimFrame(handle): void — Cancel an animation frame.
• loadImage(img, imgDesc): void — Load an image and callback with its description.
• UID(): number — Generate a unique id (GUID is an alias).
• parseJSON(str) — Parse a JSON string. Non-string or empty values are returned as-is; a parse failure throws an exception.
• removeFromArray(obj, array): void — Remove an element from an array.
• forEachCoord(arr, fn, context?) — Iterate over a multi-dimensional coordinate array and invoke the callback for each coordinate.
• interpolate(a, b, t): number — Linearly interpolate between a and b by the ratio t.
• clamp(n, min, max): number — Clamp n into the [min, max] range.
• btoa(input): string — base64 encoding.
• b64toBlob(b64Data, contentType): Blob — Convert a base64 string into a Blob.
• computeDegree(x0, y0, x1, y1): number — Compute the angle (radians) between the line connecting two points and the x-axis.
• flash(interval, count, cb, ctx): void — Flash-effect wrapper.
• isURL(url): boolean — Whether the string is a URL.
• extractCssUrl(str): string — Extract the address from a CSS url(...).