Files
openlayers/src/ol/functions.js
Tim Schaub 054af09032 Make code prettier
This updates ESLint and our shared eslint-config-openlayers to use Prettier.  Most formatting changes were automatically applied with this:

    npm run lint -- --fix

A few manual changes were required:

 * In `examples/offscreen-canvas.js`, the `//eslint-disable-line` comment needed to be moved to the appropriate line to disable the error about the `'worker-loader!./offscreen-canvas.worker.js'` import.
 * In `examples/webpack/exapmle-builder.js`, spaces could not be added after a couple `function`s for some reason.  While editing this, I reworked `ExampleBuilder` to be a class.
 * In `src/ol/format/WMSGetFeatureInfo.js`, the `// @ts-ignore` comment needed to be moved down one line so it applied to the `parsersNS` argument.
2020-04-06 12:54:09 -06:00

61 lines
1.3 KiB
JavaScript

/**
* @module ol/functions
*/
import {equals as arrayEquals} from './array.js';
/**
* Always returns true.
* @returns {boolean} true.
*/
export function TRUE() {
return true;
}
/**
* Always returns false.
* @returns {boolean} false.
*/
export function FALSE() {
return false;
}
/**
* A reusable function, used e.g. as a default for callbacks.
*
* @return {void} Nothing.
*/
export function VOID() {}
/**
* Wrap a function in another function that remembers the last return. If the
* returned function is called twice in a row with the same arguments and the same
* this object, it will return the value from the first call in the second call.
*
* @param {function(...any): ReturnType} fn The function to memoize.
* @return {function(...any): ReturnType} The memoized function.
* @template ReturnType
*/
export function memoizeOne(fn) {
let called = false;
/** @type {ReturnType} */
let lastResult;
/** @type {Array<any>} */
let lastArgs;
let lastThis;
return function () {
const nextArgs = Array.prototype.slice.call(arguments);
if (!called || this !== lastThis || !arrayEquals(nextArgs, lastArgs)) {
called = true;
lastThis = this;
lastArgs = nextArgs;
lastResult = fn.apply(this, arguments);
}
return lastResult;
};
}