在某些浏览器中，Object.keys()不会返回所有for-in 循环并hasOwnProperty()返回的键。
是否有不使用 for-in 循环的解决方法？
是否还有另一个对象window表现出相同的错误，或者它只是window对象的问题，因为我的测试倾向于显示？
澄清
两者都应该只返回自己的和唯一的可枚举属性，正如我们可以从文档中看到的那样：
- for-in 循环
hasOwnProperty()：“ for...in 循环仅迭代可枚举的属性。 ”并hasOwnProperty()从原型链中过滤掉继承的属性，只保留自己的属性。 Object.keys(): "要返回其可枚举的自身属性的对象。 "
结论：它们应该迭代相同的键：仅可枚举和拥有的属性。
浏览器结果
Firefox 39：没有丢失的密钥
Chromium 38：47 个缺失键：
["speechSynthesis", "localStorage", "sessionStorage", "applicationCache", "webkitStorageInfo", "indexedDB", "webkitIndexedDB", "crypto", "CSS", "performance", "console", "devicePixelRatio", "styleMedia", "parent", "opener", "frames", "self", "defaultstatus", "defaultStatus", "status", "name", "length", "closed", "pageYOffset", "pageXOffset", "scrollY", "scrollX", "screenTop", "screenLeft", "screenY", "screenX", "innerWidth", "innerHeight", "outerWidth", "outerHeight", "offscreenBuffering", "frameElement", "clientInformation", "navigator", "toolbar", "statusbar", "scrollbars", "personalbar", "menubar", "locationbar", "history", "screen"]
- Safari 5.1：缺少 37 个键：
["open", "moveBy", "find", "resizeTo", "clearTimeout", "btoa", "getComputedStyle", "setTimeout", "scrollBy", "print", "resizeBy", "atob", "openDatabase", "moveTo", "scroll", "confirm", "getMatchedCSSRules", "showModalDialog", "close", "clearInterval", "webkitConvertPointFromNodeToPage", "matchMedia", "prompt", "focus", "blur", "scrollTo", "removeEventListener", "postMessage", "setInterval", "getSelection", "alert", "stop", "webkitConvertPointFromPageToNode", "addEventListener", "dispatchEvent", "captureEvents", "releaseEvents"]
- Safari 14：没有丢失的密钥
测试脚本
var res = (function(obj) {
var hasOwn = Object.prototype.hasOwnProperty;
var allKeys = [];
for(var key in obj) {
if(hasOwn.call(obj, key)) {
allKeys.push(key);
}
}
var keys = Object.keys(obj);
var missingKeys = [];
for(var i = 0; i < allKeys.length; i++) {
if(keys.indexOf(allKeys[i]) === -1) {
missingKeys.push(allKeys[i]);
}
}
return {allKeys: allKeys, keys: keys, missingKeys: missingKeys};
})(window);
// This should be empty if the followings return the same set of keys:
// - for...in with hasOwnProperty()
// - Object.keys()
console.log(res.missingKeys, res.missingKeys.length);