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Mohammad Talim

Unintended side effect when using forEach loop with nested arrays in JavaScript

asked 8 months ago

2 Answers

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I'm working on a function in JavaScript that iterates through a nested array of objects. I'm using a forEach loop to modify each object within the nested arrays. However, I'm experiencing an unexpected behavior where changes made within the loop seem to be affecting all objects in the nested arrays.

Here's a simplified example of my code:

const data = [
  [ { name: "Item 1", value: 0 }, { name: "Item 2", value: 1 } ],
  [ { name: "Item 3", value: 2 }, { name: "Item 4", value: 3 } ]
];

data.forEach( innerArray => {
  innerArray.forEach( item => {
    item.value = item.value * 2;  // Doubling the value
  });
});

console.log(data); // This outputs: [[{ name: "Item 1", value: 0 }, { name: "Item 2", value: 0 }], [{ name: "Item 3", value: 0 }, { name: "Item 4", value: 0 }]] (unexpectedly all values are 0)

I expect the value property of each object in the nested arrays to be doubled. However, all values end up being 0. Can someone explain why this is happening and how I can achieve the intended behavior of modifying each object's value independently?

2 Answers

Mohammad Talim

answered 8 months ago

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Mohammad Talim

answered 6 months ago

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