froebel/throttle.js

TypeScript utility library

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = exports.cancel = void 0;
const {
  performance
} = "performance" in globalThis ? globalThis : require("perf_hooks");
const cancel = Symbol("throttle.cancel");
/**
 * Create a throttled function that invokes `fun` at most every `ms` milliseconds.
 *
 * `fun` is invoked with the last arguments passed to the throttled function.
 *
 * Calling `[throttle.cancel]()` on the throttled function will cancel the currently
 * scheduled invocation.
 */

exports.cancel = cancel;
const throttle = Object.assign((fun, ms, {
  leading = true,
  trailing = true
} = {}) => {
  let toId;
  let lastInvoke = -Infinity;
  let lastArgs;

  const invoke = () => {
    lastInvoke = performance.now();
    toId = undefined;
    fun(...lastArgs);
  };

  return Object.assign((...args) => {
    if (!leading && !trailing) return;
    lastArgs = args;
    const dt = performance.now() - lastInvoke;
    if (dt >= ms && toId === undefined && leading) invoke();else if (toId === undefined && trailing) {
      toId = setTimeout(invoke, dt >= ms ? ms : ms - dt);
    }
  }, {
    [cancel]: () => clearTimeout(toId)
  });
}, {
  cancel
});
var _default = throttle;
exports.default = _default;
module.exports = Object.assign(exports.default || {}, exports);