Check for undefined in javascript

Question

I have the following function :

/**
       * ParkingTime Duration, which is shown by the size of each circle/bubble.
       *
       * @param garage
       * @param res
       * @returns {*}
       */
      function getParkingDuration(garage, res) {
        var parking = res.parking;
        var parking_duration = Array();
        for (var j = 0; j < parking.length; j++) {
          if (typeof parking[j][garage].parkingtime != 'undefined') {
            parking_duration.push(parking[j][garage].parkingtime);
          } else {
            parking_duration.push(0.1);
          }
        }

        return parking_duration;
      }

if there is an undefined variable, i want to push a value to some array.

But when i check my console i still see some errors of parkingtime undefined.

Why the code is not reaching my else statement?

what is the actual text of the error? Might it be saying that you cannot access parkingtime of undefined, which would mean parking[j][garage] is undefined — Patrick Evans
– Patrick Evans, Commented May 23, 2016 at 13:15
can you console.log(typeof parking[j][garage].parkingtime) ? — Sofiane Sadi
– Sofiane Sadi, Commented May 23, 2016 at 13:15

mplungjan · Accepted Answer · 2016-05-23 13:24:43Z

1

My suggestion:

  function getParkingDuration(garage, res) {
    var parking = res.parking || []; // in case res is undefined
    var parking_duration = [];
    for (var j = 0; j < parking.length; j++) {
      parking_duration[j]=0.1; // default
      if (parking[j] &&
          parking[j][garage] &&
          parking[j][garage].parkingtime) {               
        parking_duration[j]=parking[j][garage].parkingtime;
      }
    }
    return parking_duration;
  }

answered May 23, 2016 at 13:24

mplungjan

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Comments

gurvinder372 · Accepted Answer · 2016-05-23 13:17:35Z

0

Not sure what your object structure is (I mean - whether you are not defining parkingtime or defining it as null or empty), you can try

if ( !isNaN(parking[j][garage].parkingtime) ) 
{
}

this should work if your parkingtime is supposed to be an Number always.

I am assuming that it always reaches inside if statement since you said

But when i check my console i still see some errors of parkingtime undefined.

answered May 23, 2016 at 13:17

gurvinder372

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Comments

Ashok kumar · Accepted Answer · 2016-05-23 13:20:04Z

0

you should use undefined without any string literals. So give like these
(parking[j][garage].parkingtime == undefined).

edited May 23, 2016 at 13:20

answered May 23, 2016 at 13:17

Ashok kumar

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1 Comment

Patrick Evans Over a year ago

typeof returns a string

Sofiane Sadi · Accepted Answer · 2016-05-23 13:22:16Z

It look like parking[j][garage] itself is undefined. Can you try this:

 /**
           * ParkingTime Duration, which is shown by the size of each circle/bubble.
           *
           * @param garage
           * @param res
           * @returns {*}
           */
          function getParkingDuration(garage, res) {
            var parking = res.parking;
            var parking_duration = Array();
            for (var j = 0; j < parking.length; j++) {
              if (typeof parking[j] == 'undefined') {
                  parking[j] = {};
              }
              if (typeof parking[j][garage] == 'undefined') {
                 parking[j][garage] = {};
              }
              if (typeof parking[j][garage].parkingtime != 'undefined') {
                parking_duration.push(parking[j][garage].parkingtime);
              } else {
                parking_duration.push(0.1);
              }
            }

            return parking_duration;
          }

Piotr Ma'niak · Accepted Answer · 2016-05-23 13:22:47Z

first of all:

var parking = res.parking; //if res is undefined you'll get an error

second:

for (var j = 0; j < parking.length; j++) { //if parking is undefined you'll get an error

3) if parking[j][garage] is undefined:

if (typeof parking[j][garage].parkingtime != 'undefined') { //will give error

That's more or less what you need:

function getParkingDuration(garage, res) {
        var parking_duration = Array();
        if(res && res.parking){
          var parking = res.parking;

          for (var j = 0; j < parking.length; j++) {
            if (garage && parking[j][garage] && typeof parking[j][garage].parkingtime != 'undefined') {
              parking_duration.push(parking[j][garage].parkingtime);
            } else {
              parking_duration.push(0.1);
          }
        }
      }

     return parking_duration;
  }

Eke Wokocha · Accepted Answer · 2016-05-23 13:35:40Z

0

Here are some things you can check quickly using console.log to see what is going on with your code

Check if res.parking is defined
Check if parking[j] is defined
Check if parking[j][garage] is defined
Check if parking[j][garage] has the attribute `parkingtime'

It will help you see what is defined and what isn't and help you to better address your problem.

answered May 23, 2016 at 13:35

Eke Wokocha

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