reactjs - how to create an array of unique items in an JSON response array?

Question

I want to push the unique items in an array to an empty array from the below response which is

Here the title key is same for many items, I want to push the unique items to an empty array for which I have written the following function which is :

const getPendingList = (data) => {
    if (data) {
      var stack = [];
      for (let i = 0; i < data.length - 1; i++) {
        if (data[i + 1].title !== data[i].title) {
          stack.push(data[i].title);
        }
      }
      console.log('stack', stack);
      return stack.length;
    }
  };

But when I console stack here, I ain't getting the last unique item :

If I change the loop to

for (let i = 0; i < data.length; i++)

for some unknown reason am getting the following error:

could anyone please let me know where have I gone wrong? Any leads would be great, kindly let me know if anything else is required for better understanding.

question from:https://stackoverflow.com/questions/65902340/how-to-create-an-array-of-unique-items-in-an-json-response-array

Answer 1

The issue is with this piece of code

for (let i = 0; i < data.length - 1; i++) {
    if (data[i + 1].title !== data[i].title) {
      stack.push(data[i].title);
    }
  }

Change data.length - 1 to data.length.