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

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 May 22 '22 at 16:49 — Code Maniac, May 22 '22 at 16:49

score 2 · Answer 1 · answered May 22 '22 at 16:48

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 '22 at 16:48

Enes Can Güneş

196
6

Thank, but the error persists. The code prints the first information, but the second array's "payload" is empty, then it returns the error. – Alex_Lima84 May 22 '22 at 16:56
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: https://pastebin.pl/view/c2c45d9a – Enes Can Güneş May 22 '22 at 20:39

Ingenious_Hans · Answer 2 · 2022-05-22T17:00:46.053

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)
        }    
      }

Thanks, but I'm receiving this error: Cannot read properties of undefined (reading 'length') — Alex_Lima84, May 22 '22 at 16:59

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

2 Answers2