I have following code:
var students = [];
for(var i = 0; i < classes.length; i++) {
var student = {};
student = classes[i].student;
student.teacher = classes[i].teacher;
students.push(student);
}
Somehow the students will print same object for all its contents, although I have put var student = {}; inside the loop, thus it must not refer to same reference.
Anyone has idea why this happens?
You put student = {} inside the loop, then on the line immediately following that one you overwrote that by assigning student = classes[i].student.
If the intention is to make a copy of whatever classes[i].student is you can use the Object.assign() method:
var student = Object.assign({}, classes[i].student);
In context:
var students = [];
for(var i = 0; i < classes.length; i++) {
var student = Object.assign({}, classes[i].student);
student.teacher = classes[i].teacher;
students.push(student);
}
(Note that Object.assign() doesn't do a deep copy - I'm not sure if that matters because you haven't shown what the classes array structure is.)
You could also use the .map() method instead of an explicit for loop:
var students = classes.map(function(c) {
var student = Object.assign({}, c.student);
student.teacher = c.teacher;
return student;
});
student: classes[i].student, it will be nested object.
classes[i].student object. Regarding your original student = classes[i].student, that assigns the student variable to refer to the same object that classes[i].student refers to.classes[i].student will have different reference, thus I thought student = classes[i].student should be working..= makes another reference to the existing object.
var student = {};assignment immediately gets invalidated by thestudent = classes[i].student;assignment. The result of those two lines if identical to running the single assignmentvar student = classes[i].student;