如何groupby在本機反應中從物件中選擇最大 ID。那只是一個虛擬資料來向您解釋我的物件的樣子
[
{"name": "alex", "subject": "english" "student_id": "1"},
{"name": "hales", "subject": "science" "student_id": "2"},
{"name": "joss", "subject": "english" "student_id": "3"},
{"name": "alexandra", "subject": "science" "student_id": "4"},
{"name": "mark", "subject": "math" "student_id": "5"},
]
首先，我想按主題分組，然后選擇具有最大 id 的學生，所以我的輸出應該是這樣的
[
{"name": "joss", "subject": "english" "student_id": "3"},
{"name": "alexandra", "subject": "science" "student_id": "4"},
{"name": "mark", "subject": "math" "student_id": "5"},
]
到目前為止，我嘗試過的是
const result = myobject.reduce(function (r, a) {
r[a.case_id] = r[a.case_id] || [];
r[a.case_id].push(a);
return r;
}, Object.create(null));
使用上面的代碼，我可以分組但無法獲得最大 ID，那么我該如何實作呢？
uj5u.com熱心網友回復：
如果值更大，您可以分組subject并替換該值。student_id
結果從物件中獲取值。
const
data = [{ name: "alex", subject: "english", student_id: "1" }, { name: "hales", subject: "science", student_id: "2" }, { name: "joss", subject: "english", student_id: "3" }, { name: "alexandra", subject: "science", student_id: "4" }, { name: "mark", subject: "math", student_id: "5" }],
result = Object.values(data.reduce((r, o) => {
if (!r[o.subject] || r[o.subject].student_id < o.student_id) {
r[o.subject] = o;
}
return r;
}, Object.create(null)));
console.log(result);.as-console-wrapper { max-height: 100% !important; top: 0; }轉載請註明出處，本文鏈接：https://www.uj5u.com/net/453635.html
標籤：javascript 反应式 目的 通过...分组