原文链接: js es10 新特性

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原文
ES10 功能完全指南

在过去的整数值大于9007199254740992不支持。如果超出，则该值将锁定为 MAX_SAFE_INTEGER + 1 ：

加法需要类型相同

const limit = Number.MAX_SAFE_INTEGER;
console.log(limit) // 9007199254740991
console.log(limit + 1) // 9007199254740992
console.log(limit + 2) // 9007199254740992const larger = 9007199254740991n;
console.log(larger, larger + 2n) // 9007199254740991n 9007199254740993nconst integer = BigInt(9007199254740991); // initialize with number
console.log(integer, integer + 2n) // 9007199254740991n 9007199254740993nconst same = BigInt("9007199254740991"); // initialize with "string" 9007199254740991n
console.log(same, same + 2n) // 9007199254740991n 9007199254740993nconsole.log(typeof 1, typeof 1n) // number bigint

数组扁平化

let multi = [1, 2, 3, [4, 5, 6, [7, 8, 9, [10, 11, 12]]]];
multi.flat();               // [1,2,3,4,5,6,Array(4)]
multi.flat().flat();        // [1,2,3,4,5,6,7,8,9,Array(3)]
multi.flat().flat().flat(); // [1,2,3,4,5,6,7,8,9,10,11,12]
multi.flat(Infinity);       // [1,2,3,4,5,6,7,8,9,10,11,12]

let array = [1, 2, 3, 4, 5]
array.map(x => [x, x * 2])
// [Array(2), Array(2), Array(2)]
// 0: (2)[1, 2]
// 1: (2)[2, 4]
// 2: (2)[3, 6]
// 3: (2)[4, 8]
// 4: (2)[5, 10]array.flatMap(v => [v, v * 2])
// [1, 2, 2, 4, 3, 6, 4, 8, 5, 10]

对象键值对遍历

let obj = {apple: 10, orange: 20, banana: 30};
let entries = Object.entries(obj);
// entries;
// (3) [Array(2), Array(2), Array(2)]
// 0: (2) ["apple", 10]
// 1: (2) ["orange", 20]
// 2: (2) ["banana", 30]
let fromEntries = Object.fromEntries(entries);
// { apple: 10, orange: 20, banana: 30 }

稳定排序

var fruit = [{name: "Apple", count: 13,},{name: "Pear", count: 12,},{name: "Banana", count: 12,},{name: "Strawberry", count: 11,},{name: "Cherry", count: 11,},{name: "Blackberry", count: 10,},{name: "Pineapple", count: 10,}
];
// Create our own sort criteria function:
let my_sort = (a, b) => a.count - b.count;
// Perform stable ES10 sort:
let sorted = fruit.sort(my_sort);
console.log(sorted);