JavaScript object - numeric key literal undefined

Question

This snippet of code has the values I list in the comments.

var studentid = course.roster[i];     // studentid = 1367
console.log(studentid);               // prints 1367
console.log(students[1367]);          // correctly prints a student object

If I change the key in the third line to use a variable with the exact same value, then the result is undefined. Why?

console.log(students[studentid]);     // fails to print correctly

This is the output from console.log(students[1367]):

Object {
    lname: "John",
    fname: "Smith",
    grade: "Sophomore",
    id: "1367",
    email: "[email protected]"
}

This is the output from console.log(students[studentid]):

undefined

may be studentid is return string

uzaif
– uzaif

2016-04-26 05:05:27 +00:00
Commented Apr 26, 2016 at 5:05 — uzaif
– uzaif, Commented Apr 26, 2016 at 5:05
does this solve your problem?

uzaif
– uzaif

2016-04-26 05:07:27 +00:00
Commented Apr 26, 2016 at 5:07 — uzaif
– uzaif, Commented Apr 26, 2016 at 5:07

uzaif · Accepted Answer · 2016-04-26 05:11:10Z

2

The problem is

var studentid = course.roster[i];     // studentid = 1367

its return string and your id in integer so try to convert the studentid into string

var studentid = parseInt(course.roster[i]);     // studentid = 1367

which will work in your case

answered Apr 26, 2016 at 5:11

uzaif

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Comments

pillys · Accepted Answer · 2016-04-26 05:07:02Z

0

try to parse the string id to number.

console.log(students[Number(studentid)]);

answered Apr 26, 2016 at 5:07

pillys

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