Question 182638 in Javascript Question posted in
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Javascript – Check if prev id in a loop is not same as current

Lets say there is an array of objects

array = [{ id : 1, name : 'aaa' }, { id : 1, name: 'asd' }, id : 2, name : 'asd' ]

in a loop eg

array.forEach(a =>{ currentId = a.id }

how to check if current id is same or not as prev id

Tags:

2

Answers


  1. 0

    You can use the index to get the previous entry:

    array = [{ id : 1, name : 'aaa' }, { id : 1, name: 'asd' }, {id : 2, name : 'asd'} ]

array.forEach((a, index) =>{
  let currentId = a.id

  // Check if previous exists (Index will be 0 on first run)
  if (index) {
    let previousId = array[index - 1].id
    // If exists we can check it
    console.log(currentId === previousId)
  }
})
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  2. 0

    You can use reduce like:

    const array = [{
  id: 1,
  name: 'aaa'
}, {
  id: 1,
  name: 'bbb'
}, {
  id: 2,
  name: 'cccc'
},
{
  id:2,
  name:'ddd'
}];

array.reduce((prev, next) => {
    if (prev.id === next.id) {
      console.log(`${prev.name} has same id of ${next.name}`);
    }
    return next;
});
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