共计 1989 个字符,预计需要花费 5 分钟才能阅读完成。
通常须要查看值是否符合条件而且值在对象中,这里有一些办法,能够应用一些 () every () 和 Object.values ()来实现这一点
Object.values
Value 用于依据 Object 中的值创立数组。传递一个对象到 Object.values,它将返回一个值数组
const stock = { | |
meat: 5, | |
fruit: 10, | |
cheese: 6, | |
} | |
const valueArray = Object.values(stock) | |
// [5, 10, 6] |
some()
如果依据传入的条件有一个符合条件,some ()返回 true。如果没有,它将返回 false
const stock = { | |
meat: 5, | |
fruit: 10, | |
cheese: 6, | |
} | |
const enoughStock = Object.values(stock).some(el => el >= 6) | |
console.log(enoughStock) // true |
const kidsParty = { | |
suzy: 12, | |
bill: 4, | |
tim: 2, | |
sally: 5, | |
ming: 3, | |
} | |
const isAdultPresent = Object.values(kidsParty).some(el => el >= 18) | |
console.log(isAdultPresent) //false |
every()
Every ()依据条件返回 true 或 false,如果每一项都符合条件
const nightclub = { | |
dave: 26, | |
sally: 23, | |
mike: 17, | |
lucy: 18, | |
} | |
const isOldEnough = Object.values(nightclub).every(el => el >= 18) | |
// false | |
if (!isOldEnough) {console.log("Check every ID") | |
} |
检测数组中的每一项是否符合要求
const computers = [{name:"Apple",ram:8}, | |
{name:"IBM",ram:4}, | |
{name:"Acer",ram:32}, | |
]; | |
var result= computers.every(function(computer){return computer.ram > 16}) | |
console.log(result)//false; | |
var some = computers.some(function(computer){return computer.ram > 16}) | |
console.log(some)//true; |
拓展 Object.entries()
Object.entries() 办法返回一个给定对象本身可枚举属性的 键值对数组 ,其 排列 与应用 for…in 循环遍历该对象时返回的程序统一(区别在于 for-in 循环也枚举 原型链中的属性
传入对象
const obj = {foo: 'bar', baz: 'abc'}; | |
console.log(Object.entries(obj)); // [['foo', 'bar'], ['baz', 'abc']] |
数组
const arr = [1, 2, 3]; | |
console.log(Object.entries(arr)); // [['0', 1], ['1', '2'], ['2', '3']] |
数组(数组中蕴含对象)
const arr1 = [{a: 1}, 2, 3]; | |
console.log(Object.entries(arr1)); // [['0', { a: 1}], ['1', '2'], ['2', '3']] |
数组(数组中的值全副为对象)
const arr2 = [{a: 1}, {b: 2}, {c: 3}]; | |
console.log(Object.entries(arr2)); // [['0', { a: 1}], ['1', { b: 2}], ['2', { c: 3}]] |
字符串
const str = '123'; | |
console.log(Object.entries(str)); // [['0', '1'], ['1', '2'], ['2', '3']] |
数字、浮点数
const num = 123; | |
console.log(Object.entries(num)); // [] | |
const float1 = 12.3; | |
console.log(Object.entries(float1)); // [] |
将 Object 转化为 Map
new Map() 构造函数承受一个可迭代的 entries。借助 Object.entries 办法你能够很容易的将 Object 转换为 Map:
const obj2 = {foo: 'bar', baz: 'abc'}; | |
console.log(Object.entries(obj2)); // [['foo', 'bar'], ['baz', 'abc']] | |
const map = new Map(Object.entries(obj2)); | |
console.log(map); // Map {'foo' => 'bar', 'baz' => 'abc'} |
其余办法
正文完
发表至: javascript
2020-10-21