用例
这个用例是根据提供的字符串或函数将对象数组转换为哈希映射,并将其作为哈希映射中的键来计算和使用,并将值作为对象本身。使用这种方法的常见情况是将对象数组转换为对象的哈希映射。
Code
下面是一个JavaScript小片段,用于将对象数组转换为哈希映射,以object的属性值为索引。您可以提供一个函数来动态计算散列映射的键(运行时)。
function isFunction(func) {
return Object.prototype.toString.call(func) === '[object Function]';
}
/**
* This function converts an array to hash map
* @param {String | function} key describes the key to be evaluated in each object to use as key for hashmap
* @returns Object
* @Example
* [{id:123, name:'naveen'}, {id:345, name:"kumar"}].toHashMap("id")
* Returns :- Object {123: Object, 345: Object}
*
* [{id:123, name:'naveen'}, {id:345, name:"kumar"}].toHashMap(function(obj){return obj.id+1})
* Returns :- Object {124: Object, 346: Object}
*/
Array.prototype.toHashMap = function(key) {
var _hashMap = {}, getKey = isFunction(key)?key: function(_obj){return _obj[key];};
this.forEach(function (obj){
_hashMap[getKey(obj)] = obj;
});
return _hashMap;
};
你可以在这里找到要点:将数组对象转换为HashMap。
try
let toHashMap = (a,f) => a.reduce((a,c)=> (a[f(c)]=c,a),{});
让arr = (
{id: 123,名字:“弄”},
{id: 345,名字:“kumar”}
];
让fkey = o => o.id;//函数将对象更改为字符串(key)
让toHashMap = (f) = > a.reduce ((a、c) = > ((f (c)) = c, a), {});
console.log(toHashMap(arr,fkey));
//不推荐添加到原型:
//
// Array.prototype.toHashMap = function(f){返回toHashMap(this,f)};
// console.log(arr.toHashMap(fkey));
以下是我在javascript中创建的一个小片段,将对象数组转换为哈希映射,由对象的属性值索引。您可以提供一个函数来动态计算散列映射的键(运行时)。
function isFunction(func){
return Object.prototype.toString.call(func) === '[object Function]';
}
/**
* This function converts an array to hash map
* @param {String | function} key describes the key to be evaluated in each object to use as key for hasmap
* @returns Object
* @Example
* [{id:123, name:'naveen'}, {id:345, name:"kumar"}].toHashMap("id")
Returns :- Object {123: Object, 345: Object}
[{id:123, name:'naveen'}, {id:345, name:"kumar"}].toHashMap(function(obj){return obj.id+1})
Returns :- Object {124: Object, 346: Object}
*/
Array.prototype.toHashMap = function(key){
var _hashMap = {}, getKey = isFunction(key)?key: function(_obj){return _obj[key];};
this.forEach(function (obj){
_hashMap[getKey(obj)] = obj;
});
return _hashMap;
};
你可以在这里找到要点:https://gist.github.com/naveen-ithappu/c7cd5026f6002131c1fa