如何在 JavaScript 中按值对地图进行排序？

Question

如何按值对这张地图进行排序？

 var map = new Map();
map.set('orange', 10);
map.set('apple', 5);
map.set('banana', 20);
map.set('cherry', 13);

原文由 chenxinlong 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

你可以采取不同的方法并更改 Symbol.iterator 的 Map.prototype[@@iterator]() 以获得自定义排序结果。

 var map = new Map();

map.set("orange", 10);
map.set("apple", 5);
map.set("banana", 20);
map.set("cherry", 13);

map[Symbol.iterator] = function* () {
    yield* [...this.entries()].sort((a, b) => a[1] - b[1]);
}

for (let [key, value] of map) {     // get data sorted
    console.log(key + ' ' + value);
}

console.log([...map]);              // sorted order
console.log([...map.entries()]);    // original insertation order

 .as-console-wrapper { max-height: 100% !important; top: 0; }

原文由 Nina Scholz 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

const myMap = new Map();
myMap.set("a",3);
myMap.set("c",4);
myMap.set("b",1);
myMap.set("d",2);

// sort by value
const mapSort1 = new Map([...myMap.entries()].sort((a, b) => b[1] - a[1]));
console.log(mapSort1);
// Map(4) {"c" => 4, "a" => 3, "d" => 2, "b" => 1}

const mapSort2 = new Map([...myMap.entries()].sort((a, b) => a[1] - b[1]));
console.log(mapSort2);
// Map(4) {"b" => 1, "d" => 2, "a" => 3, "c" => 4}

// sort by key
const mapSort3 = new Map([...myMap.entries()].sort());
console.log(mapSort3);
// Map(4) {"a" => 3, "b" => 1, "c" => 4, "d" => 2}

const mapSort4 = new Map([...myMap.entries()].reverse());
console.log(mapSort4);
// Map(4) {"d" => 2, "b" => 1, "c" => 4, "a" => 3}

原文由 Miroslav Savovski 发布，翻译遵循 CC BY-SA 4.0 许可协议