我正在嘗試減少 Chrome 擴(kuò)展中的全局變量，以減少 JavaScript 中的“意大利面”或歧義。我試圖通過(guò)一個(gè) init 函數(shù)來(lái)嘗試此操作，該函數(shù)在 mousedown eventListener 回調(diào)函數(shù)中聲明這些全局變量，該函數(shù)可能會(huì)被多次觸發(fā)。這樣我就可以將這些變量+事件作為此類(lèi)回調(diào)的參數(shù)傳遞給其他 eventListener 回調(diào)（即 mouseup 回調(diào)）。我已將問(wèn)題分解為一個(gè)單獨(dú)的文件：索引.html<!doctype html><html><head> <meta charset="utf-8"></head><body> <script src="test.js"></script></body></html>測(cè)試.jsisVarsInitOnce = false;function executesMoreThanOnce() { const initVariables = function() { console.log('runs once'); const bools = { boolOne: false, boolTwo: false, boolThree: false }; const events = { clickEvent: function(event) { //do stuff }, keyEvent: function(event) { //do other stuff } }; return { bools: bools, events: events } }; if (!isVarsInitOnce) { isVarsInitOnce = true; let vars = initVariables(); var booleanObject = vars.bools; var eventObject = vars.events; } console.log('objects: ', booleanObject, eventObject); //attempting to access initialised variable after function is executed more than once will cause an error. //this is because the booleanObject is now undefined. booleanObject.boolOne = true;}//runs twicefor (let i=0; i<2; i++) { executesMoreThanOnce();}我用來(lái)控制執(zhí)行的方法initVariables()是一個(gè)全局布爾變量，isVarsInitOnce它可以有效地初始化變量并設(shè)置executesMoreThanOnce()一次在函數(shù)中使用的對(duì)象?？梢栽谘h(huán)中調(diào)用該函數(shù)的第一個(gè)實(shí)例中訪(fǎng)問(wèn)這些for對(duì)象，但是undefined當(dāng)嘗試在循環(huán)中調(diào)用該函數(shù)的第二個(gè)實(shí)例中訪(fǎng)問(wèn)這些對(duì)象時(shí)，就會(huì)訪(fǎng)問(wèn)這些對(duì)象for。這在控制臺(tái)輸出中非常清楚地表示出來(lái)：runs oncetest.js:38 objects: {boolOne: false, boolTwo: false, boolThree: false} {clickEvent: ?, keyEvent: ?}test.js:38 objects: undefined undefined //<--- (function called 2nd time)test.js:42 Uncaught TypeError: Cannot set property 'boolOne' of undefined at executesMoreThanOnce (test.js:42) at test.js:47我不確定為什么會(huì)發(fā)生這種情況。誰(shuí)能幫助我理解為什么這不能正常工作？對(duì)于我的情況，有人有更好的建議來(lái)減少全局變量嗎？非常感謝。
JS| 訪(fǎng)問(wèn)該對(duì)象的函數(shù)多次運(yùn)行后，初始化對(duì)象未定義
一只名叫tom的貓
2023-09-21 10:48:56
