ut2/lib/internals/baseDebounce.js

一个现代 JavaScript 实用工具库。[点击查看在线文档]。

'use strict';

var defaultTo = require('../defaultTo.js');
var toNumber = require('../toNumber.js');
var helpers = require('./helpers.js');
var native = require('./native.js');

function baseDebounce(func, wait, immediate, __throttle__) {
    if (__throttle__ === void 0) { __throttle__ = false; }
    if (typeof func !== 'function') {
        throw new TypeError(helpers.FUNC_ERROR_TEXT);
    }
    var timer, lastCallTime, lastInvokeTime, lastArgs, lastThis, result;
    wait = defaultTo(toNumber(wait), 0);
    function shouldInvoke(time) {
        if (lastCallTime === native.nativeUndefined) {
            return true;
        }
        var timeSinceLastCall = time - lastCallTime;
        var timeSinceLastInvoke = time - lastInvokeTime;
        return timeSinceLastCall >= wait || timeSinceLastCall < 0 || (__throttle__ && timeSinceLastInvoke >= wait);
    }
    function invokeFunc(time) {
        lastInvokeTime = time;
        result = func.apply(lastThis, lastArgs);
        lastThis = lastArgs = native.nativeUndefined;
        return result;
    }
    function debounced() {
        var args = [];
        for (var _i = 0; _i < arguments.length; _i++) {
            args[_i] = arguments[_i];
        }
        lastThis = this;
        lastArgs = args;
        var time = Date.now();
        var isInvoke = shouldInvoke(time);
        var waitTime = !__throttle__ ? wait : !isInvoke && lastCallTime !== native.nativeUndefined && timer === native.nativeUndefined ? wait - (time - lastCallTime) : wait;
        lastCallTime = time;
        if (isInvoke) {
            if (immediate && timer === native.nativeUndefined) {
                return invokeFunc(time);
            }
        }
        if (timer !== native.nativeUndefined && !__throttle__) {
            clearTimeout(timer);
            timer = native.nativeUndefined;
        }
        if (timer === native.nativeUndefined) {
            timer = setTimeout(function () {
                timer = native.nativeUndefined;
                invokeFunc(Date.now());
            }, waitTime);
        }
        return result;
    }
    function cancel() {
        if (timer !== native.nativeUndefined) {
            clearTimeout(timer);
            timer = native.nativeUndefined;
        }
        lastCallTime = timer = lastArgs = lastThis = native.nativeUndefined;
    }
    function flush() {
        if (timer !== native.nativeUndefined) {
            clearTimeout(timer);
            timer = native.nativeUndefined;
            return invokeFunc(Date.now());
        }
        return result;
    }
    function pending() {
        return timer !== native.nativeUndefined;
    }
    debounced.cancel = cancel;
    debounced.flush = flush;
    debounced.pending = pending;
    return debounced;
}

module.exports = baseDebounce;