它们都返回一个遍历器对象,可以用for…of循环进行遍历,唯一的区别是keys()是对键名的遍历、values()是对键值的遍历,entries()是对键值对的遍历. 1. Array的keys()和values()还有entries()方法 let arr = ['a', 'b', 'c']for(let index of arr.keys()) { console.
stringify(fun(array)); groups[group]=groups[group] || []; groups[group].push(array); }); return Object.keys(groups).map(function(group){ return groups[group] }) }; //使用groupBy函数 let result=groupBy(datas,function(item){ return item.name; //根据name分组 }); console.log(result);...
但是请注意,为了完全符合 ES3 标准,你可能还需要对一些内置函数进行补丁(polyfill),比如 Object.keys 或Array.prototype.forEach。// 输入const foo = null;export { foo as void };// 设置 reservedNamesAsProps 为 false 的 cjs 输出const foo = null;exports['void'] = foo;// 设置 reservedNamesAs...
functionmakeComplicatedObject(){ const obj=Object.fromEntries(Array.from({ length:100}).map((_,index)=>[`key_${index}`,`value_${index}`]))returnobj }// 结果:100 个键值对,原型链 100 层深度const deeplyNestedObject=Array.from({ length:100}).reduce((prevObj,_current,index)=>{ let new...
arrayValue = [[NSArray arrayWithObjects:@"text", [NSNumbernumberWithInt:30], nil] retain]; dateValue = [[NSDate date] retain]; dictValue = [[NSDictionary dictionaryWithObjectsAndKeys:@"value1",@"key1", @"value2", @"key2", @"value3", @"key3", nil] retain]; ...
You can minify more than one JavaScript file at a time by using an object for the first argument where the keys are file names and the values are source code: var code = { "file1.js": "function add(first, second) { return first + second; }", "file2.js": "console.log(add(1 ...
除了Object类型之外,Array类型恐怕是js中最常用的类型了,并且随着js的发展进步,数组中提供的方法也越来越来,对数组的处理也出现了各种骚操作。 如果对js原型/原型链不了解的可以移步_深入了解javascript原型/原型链,_下面我们就来一起学习下js的数组。
FixedArray* keys = nullptr; Map* original_map = object->map(); if (original_map->HasEnumCache()) { if (object->HasNoElements()) { keys = original_map->GetCachedEnumKeys(); } else { keys = object->GetCachedEn...
FixedArray and length <= elements.length();// Please note: push and pop can be used to grow and shrink the array.// - slow, backing storage is a HashTable with numbers as keys.classJSArray:publicJSObject{public:// [length]: The length property.DECL_ACCESSORS(length,Object)// ...}...
——就是中间这种,通过Array后边再加一个.号的方式定义数组类型。这是 JSDoc 的标准,所以也是支持的。 也支持使用Object.<A, B>表示 Mapped type,等价于Record: /*** A map-like object that maps arbitrary `string` properties to `number`s.** @type {Object.<string, number>}*/letstringToNumber; ...