Inside an array, how to check forript? - object

Question

So I will be constantly retrieving an object with the following format:
student: {
"student_id": "12345",
"location": "below",
},
]
},
]
Thank you and will accept answer and upvote!

Answer 1

Something like this should do the trick:
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);
}
You would then invoke it as follows:
addStudent({
"student_id": "67890",
"class_number": "abcd",
"location": "below",
});
Runnable JSBin example available here.
More available on Array.prototype.find at MDN.

Answer 2

This problem can be solved using indexing by student_id. For example:
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]);
}
You can use also result format that contains objects, indexed by student_id or plain array resultArray.