JavaScript error: Cannot read properties of undefined (reading '1') [duplicate]

Question

I have the code bellow and I'm trying to console.log the information from message of each array. The problem is there are some undefined "payload". What can I do to ignore the undefined values and keep iterating through the arrays?

const repositoriesActivities = await getUserActivities(userName)
   
    for (let i = 0; i < repositoriesActivities.length; i++) {
        let activities = repositoriesActivities[i].payload.commits[i].message;
        
        if (activities !== undefined){
           console.log(activities)
        }    
      }

You can use optional chaining ?.

Code Maniac
– Code Maniac

2022-05-22 16:49:14 +00:00
Commented May 22, 2022 at 16:49 — Code Maniac
– Code Maniac, Commented May 22, 2022 at 16:49

Enes Can Güneş · Accepted Answer · 2022-05-22 16:48:35Z

2

You can use ? operand to check. Example:

const repositoriesActivities = await getUserActivities(userName)
   
    for (let i = 0; i < repositoriesActivities.length; i++) {
        let activities = repositoriesActivities[i]?.payload?.commits[i]?.message;
        
        if (activities){
           console.log(activities)
        }    
      }

Check this to get more information about optional chaining https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining

answered May 22, 2022 at 16:48

Enes Can Güneş

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2 Comments

Alex_Lima84 Over a year ago

Thank, but the error persists. The code prints the first information, but the second array's "payload" is empty, then it returns the error.

Enes Can Güneş Over a year ago

Hi, maybe there is something that we missed. Can you check this code. I have created a simple array and using for loop. After 2 steps you can see we get different console on this example: pastebin.pl/view/c2c45d9a

Hans Murangaza DRCongo · Accepted Answer · 2022-05-22 17:00:46Z

1

this means the object "commits" is empty. Can you try:

const repositoriesActivities = await getUserActivities(userName)
   
    for (let i = 0; i < repositoriesActivities.length; i++) {
        let activities = null
if(repositoriesActivities[i] && repositoriesActivities[i].payload && typeof repositoriesActivities[i].payload.commits === "object" && repositoriesActivities[i].payload.commits.length >= (i+1) && repositoriesActivities[i].payload.commits[i].message){
   activities = repositoriesActivities[i].payload.commits[i].message
} 
   
        
        if (activities !== null){
           console.log(activities)
        }    
      }

edited May 22, 2022 at 17:00

answered May 22, 2022 at 16:51

Hans Murangaza DRCongo

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1 Comment

Alex_Lima84 Over a year ago

Thanks, but I'm receiving this error: Cannot read properties of undefined (reading 'length')

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