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how to loop through array (array of objects) starting at a specific index to the last and alter properties in the object in Javascript?

let library = []; //this stores each object

Each object has a property called' id' where a number is stored, this represents the index of the object in the library array. Basically when an object is deleted from the library I want to get all the objects in the array that come after the deleted object and minus 1 from the id property.

function updateId(index) {
  for (let i = index; i <= library.length; i++) {
    library[i].id - 1;
  }
}

So far I have this function where the argument index is the position in the array where the object was deleted. I am getting a reference error with that last line of code

about 4 years ago · Juan Pablo Isaza

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Answer 1 · 2022-07-11T13:55:58.317Z

Instead of i <= library.length try i < library.length.

Currently that line is saying "continue this for loop so long as i is less than or equal to the length" ... but remember, i (ie. indices) are zero-based, while lengths aren't. This means that you'll actually loop past where you want.

Answer 2 · 2022-07-11T13:55:58.323Z

Note this is just one of many ways to solve this! You're almost there. There are a few things that your code needs:

to have access to the 'library' inside of your function, you should pass it into the function. Functions should only operate on variables that they received as arguments.
your for loop, should go on if i is SMALLER THAN not SMALLER EQUAL to the length
if you're changing the 'library' in a function, you need to return it, and overwrite the original.

function updateId(library, startingAtIndex) {
      for (let i = startingAtIndex; i < library.length; i++) {
        library[i].id -= 1;
      }
      return library
 }
 
things = [{name:'a', id:1},{name:'c', id:3},{name:'d', id:4}]
things = updateId(things, 1)
console.log(things)

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how to loop through array (array of objects) starting at a specific index to the last and alter properties in the object in Javascript?

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