在數組中，如何檢查forript？

Question

所以我會不斷地檢索與以下格式的對象：

student: { 
    "student_id": "12345", 

       "location": "below", 
      }, 
     ] 
    }, 
] 

謝謝你，將接受答案，並給予好評！

Answer 1

像這樣的東西應該做的伎倆：

var students = []; 

function addStudent(student) { 
    // Check if we already know about this student. 
    var existingRecord = students.find(function (s) { 
    return s.student_id === student.student_id; 
    }); 

    var classInfo = { 
    class_number: student.class_number, 
    location: student.location 
    }; 

    if (!existingRecord) { 
    // This is the first record for this student so we construct 
    // the complete record and add it. 
    students.push({ 
     student_id: student.student_id, 
     classes: [classInfo] 
    }); 

    return; 
    } 

    // Add to the existing student's classes. 
    existingRecord.classes.push(classInfo); 
} 

你可以這樣調用它，如下所示：可用here

addStudent({ 
    "student_id": "67890", 
    "class_number": "abcd", 
    "location": "below", 
}); 

Runnable的JSBin例子。

更多信息請登陸Array.prototype.findat MDN。

Answer 2

此問題可以通過使用索引student_id來解決。例如：

var sourceArray = [{...}, {...}, ...]; 

var result = {}; 

sourceArray.forEach(function(student){ 

    var classInfo = { 
     class_number: student.class_number, 
     location : student.location 
    }; 

    if(result[student.student_id]){ 

     result[student.student_id].classes.push(classInfo); 

    } else { 

     result[student.student_id] = { 
      student_id : student.student_id, 
      classes  : [classInfo] 
     } 

    } 
}); 


// Strip keys: convert to plain array 

var resultArray = []; 

for (key in result) { 
    resultArray.push(result[key]); 
} 

您還可以使用result格式包含對象，通過student_id或純陣列resultArray索引。