Iterating through a JavaScript Object

Question

Having trouble accessing objects. They are printing as undefined. Help! I need the code to print the student names.

let students = [
        {name: 'Remy', cohort: 'Jan'},
        {name: 'Genevieve', cohort: 'March'},
        {name: 'Chuck', cohort: 'Jan'},
        {name: 'Osmund', cohort: 'June'},
        {name: 'Nikki', cohort: 'June'},
        {name: 'Boris', cohort: 'June'}
    ];



    function objPrint() {
        for (var i=0; i<students.length; i++) {
           console.log("Name: " + students[i][0] + " Cohort: " + students[i][1])
        }
    }

have you tried forEach? w3schools.com/jsref/jsref_forEach.asp — Andy
– Andy, Commented Oct 1, 2018 at 17:15
Well, students[i] is not an array, students[i] is an object containing name and cohort properties. So instead of doing students[i][0], you want to do students[i].name. — nbokmans
– nbokmans, Commented Oct 1, 2018 at 17:15

NAVIN · Accepted Answer · 2018-10-01 17:21:18Z

3

Do something like this:

let students = [
    {name: 'Remy', cohort: 'Jan'},
    {name: 'Genevieve', cohort: 'March'},
    {name: 'Chuck', cohort: 'Jan'},
    {name: 'Osmund', cohort: 'June'},
    {name: 'Nikki', cohort: 'June'},
    {name: 'Boris', cohort: 'June'}
];



function objPrint() {
    for (var i=0; i<students.length; i++) {
       // Can also use students[i]['name'] , students[i]['cohort']
       // using lodash.js _.get(students, [i, 'name'], 'default value');
       // using new destructuring let {name, cohort} = students[i] then console.log("name: "+ name + " Cohort: "+cohort);
       console.log("Name: " + students[i].name + " Cohort: " + students[i].cohort);
    }
}

answered Oct 1, 2018 at 17:21

NAVIN

3,3174 gold badges21 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Sushanth -- · Accepted Answer · 2018-10-01 17:17:11Z

3

You are accessing the items as if it is an array. But in reality is it an array of objects.

The top level, already gets the item that is the current item, just access the keys with dot or bracket notation to get the value.

let students = [
        {name: 'Remy', cohort: 'Jan'},
        {name: 'Genevieve', cohort: 'March'},
        {name: 'Chuck', cohort: 'Jan'},
        {name: 'Osmund', cohort: 'June'},
        {name: 'Nikki', cohort: 'June'},
        {name: 'Boris', cohort: 'June'}
    ];
    
    students.forEach((item) => {
       //console.log(`Name - ${item.name} :: Cohort - ${item.cohort}`);
       console.log('Name - ' + item.name + " :: Cohort - " + item.cohort );
    });

answered Oct 1, 2018 at 17:17

Sushanth --

55.8k9 gold badges70 silver badges109 bronze badges

Comments

Pritam Banerjee · Accepted Answer · 2018-10-01 17:17:22Z

1

You need to call the key/attribute like this : students[i].name and then the method objPrint() to print the values.

let students = [
        {name: 'Remy', cohort: 'Jan'},
        {name: 'Genevieve', cohort: 'March'},
        {name: 'Chuck', cohort: 'Jan'},
        {name: 'Osmund', cohort: 'June'},
        {name: 'Nikki', cohort: 'June'},
        {name: 'Boris', cohort: 'June'}
    ];



    function objPrint() {
        for (var i=0; i<students.length; i++) {
           console.log("Name: " + students[i].name + " Cohort: " + students[i].cohort)
        }
    }
    
    objPrint();

answered Oct 1, 2018 at 17:17

Pritam Banerjee

19.1k10 gold badges97 silver badges113 bronze badges

Comments

user7896971 · Accepted Answer · 2018-10-01 17:18:12Z

0

Properties of objects are access by the dot notation rather than a bracket with number. So you should do it like this

students[i].name

answered Oct 1, 2018 at 17:18

user7896971

Comments

tomer raitz · Accepted Answer · 2018-10-01 17:42:08Z

0

Try this:

let students = [
        {name: 'Remy', cohort: 'Jan'},
        {name: 'Genevieve', cohort: 'March'},
        {name: 'Chuck', cohort: 'Jan'},
        {name: 'Osmund', cohort: 'June'},
        {name: 'Nikki', cohort: 'June'},
        {name: 'Boris', cohort: 'June'}
    ];

function sobjPrint() {
  for (var i in students) {

    if (students.hasOwnProperty(i)) {
       console.log("Name: " + students[i].name + " Cohort: " + students[i].cohort)
    }
  }
}

answered Oct 1, 2018 at 17:42

tomer raitz

3902 silver badges10 bronze badges

Comments

Amir · Accepted Answer · 2018-10-01 17:45:25Z

0

Try for..of:

let students = [
    {name: 'Remy', cohort: 'Jan'},
    {name: 'Genevieve', cohort: 'March'},
    {name: 'Chuck', cohort: 'Jan'},
    {name: 'Osmund', cohort: 'June'},
    {name: 'Nikki', cohort: 'June'},
    {name: 'Boris', cohort: 'June'}
]
// returns an object as a student
for(let student of students) {
 console.log(`Name: ${student.name} Cohort: ${student.cohort}`)
}

therefore u have access to object's attributes and u can do whatever.

benefits of this approach

unlike .foreach() it works with break, continue, and return
it avoids all the pitfalls of for–in (working with indexes and not objects)

and also.. use backticks to avoid the old fashioned way of string concatenation - it looks better :)

edited Oct 1, 2018 at 17:45

answered Oct 1, 2018 at 17:39

Amir

3512 silver badges6 bronze badges

Collectives™ on Stack Overflow

Iterating through a JavaScript Object

6 Answers 6

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related