lodash 基于属性的唯一性

Question

我有一个对象数组，例如

[{ "name": "Jen", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Jen", "age":32, "eyecolor": "green", "hair":"blonde"}, 
 { "name": "Jules", "age":31, "eyecolor": "blue", "hair":"brown"}, ,
 { "name": "Brian", "age":40, "eyecolor": "blue", "hair":"brown"}]

我需要一个 lodash 表达式，它会产生一组基于一个属性的唯一对象。例如，如果我使用 name，它会给我这三个：

[{ "name": "Jen", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Jules", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Brian", "age":40, "eyecolor": "blue", "hair":"brown"}]

Answer 1

对于 Lodash 版本 4+，请使用 _.uniqBy():

var arr = [{"name":"Jen","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Jen","age":32,"eyecolor":"green","hair":"blonde"},{"name":"Jules","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Brian","age":40,"eyecolor":"blue","hair":"brown"}];

var unique = _.uniqBy(arr, 'name');

console.log(unique);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

对于 4 以下的 Lodash 版本，请使用 _.uniq():

var arr = [{"name":"Jen","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Jen","age":32,"eyecolor":"green","hair":"blonde"},{"name":"Jules","age":31,"eyecolor":"blue","hair":"brown"},{"name":"Brian","age":40,"eyecolor":"blue","hair":"brown"}];

var unique = _.uniq(arr, 'name');

console.log(unique);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.10.1/lodash.js"></script>

Answer 2

如果你的 lodash 版本高于 4.0，你应该使用_.uniqBy()。

此时_.uniq()不起作用，它只接受一个参数，不能寻址迭代对象。

var arr = [{ "name": "Jen", "age":31, "eyecolor": "blue", "hair":"brown"}, 
 { "name": "Jen", "age":32, "eyecolor": "green", "hair":"blonde"}, 
 { "name": "Jules", "age":31, "eyecolor": "blue", "hair":"brown"},
 { "name": "Brian", "age":40, "eyecolor": "blue", "hair":"brown"}];

var result = _.uniqBy(arr, 'name');
console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

参考
https://lodash.com/docs/4.17.4#uniqBy