ECMAScript 5有数组类型的filter()原型，但没有对象类型，如果我理解正确的话。
我如何在JavaScript中实现对象的过滤器()?
假设我有这个对象:
var foo = {
bar: "Yes"
};
我想写一个过滤器()，工作在对象:
Object.prototype.filter = function(predicate) {
var result = {};
for (key in this) {
if (this.hasOwnProperty(key) && !predicate(this[key])) {
result[key] = this[key];
}
}
return result;
};
当我在下面的演示中使用它时，这是有效的，但是当我将它添加到使用jQuery 1.5和jQuery UI 1.8.9的站点时，我在FireBug中得到JavaScript错误。
Object.prototype.filter = function(predicate) {
var result = {};
for (key in this) {
if (this.hasOwnProperty(key) && !predicate(this[key])) {
console.log("copying");
result[key] = this[key];
}
}
return result;
};
var foo = {
bar: "Yes",
moo: undefined
};
foo = foo.filter(function(property) {
return typeof property === "undefined";
});
document.getElementById('disp').innerHTML = JSON.stringify(foo, undefined, ' ');
console.log(foo);
#disp {
white-space: pre;
font-family: monospace
}
<div id="disp"></div>
ES6进近...
假设你有下面这个对象:
const developers = {
1: {
id: 1,
name: "Brendan",
family: "Eich"
},
2: {
id: 2,
name: "John",
family: "Resig"
},
3: {
id: 3,
name: "Alireza",
family: "Dezfoolian"
}
};
创建一个函数:
const filterObject = (obj, filter, filterValue) =>
Object.keys(obj).reduce((acc, val) =>
(obj[val][filter] === filterValue ? acc : {
...acc,
[val]: obj[val]
}
), {});
叫它:
filterObject(developers, "name", "Alireza");
并将返回:
{
1: {
id: 1,
name: "Brendan",
family: "Eich"
},
2: {
id: 2,
name: "John",
family: "Resig"
}
}
我只是想添加我这样做的方式，因为它节省了我创建额外的函数，我认为更干净，我没有看到这个答案:
let object = {a: 1, b: 2, c: 3};
[object].map(({a,c}) => ({a,c}))[0]; // {a:1, c:2}
最酷的是，它也适用于对象数组:
let object2 = {a: 4, b: 5, c: 6, d: 7};
[object, object2].map(({a,b,c,d}) => ({a,c})); //[{"a":1,"c":3},{"a":4,"c":6}]
[object, object2].map(({a,d}) => ({a,d})); //[{"a":1,"d":undefined},{"a":4,"d":7}]
从2020年开始，香草JS解决方案。
let romNumbers={'I':1,'V':5,'X':10,'L':50,'C':100,'D':500,'M':1000}
你可以通过键来过滤romNumbers对象:
const filteredByKey = Object.fromEntries(
Object.entries(romNumbers).filter(([key, value]) => key === 'I') )
// filteredByKey = {I: 1}
或者根据值过滤romNumbers对象:
const filteredByValue = Object.fromEntries(
Object.entries(romNumbers).filter(([key, value]) => value === 5) )
// filteredByValue = {V: 5}
