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Strange behavior of an array filled by Array.prototype.fill()

차정 2022. 11. 2. 19:07

https://stackoverflow.com/questions/41121982/strange-behavior-of-an-array-filled-by-array-prototype-fill

 

Strange behavior of an array filled by Array.prototype.fill()

I face something I don't understand with an array. Indeed, I created an array I have filled with empty subArrays to obtain a 2D Matrix. But when I manipulate the array it doesn't behave as I expect...

stackoverflow.com

 

fill이라는걸 알게됐는데, fill은 primitive 타입에만 써야함.

fill([]) 해버리면 동일한 배열 참조하게해버림

var arr = new Array(5).fill([])

//arr[0] = arr[1] = arr[2] = arr[3] = arr[4] = [];

arr[2].push("third rank item");

console.log(arr);

//[ [ 'third rank item' ],
//  [ 'third rank item' ],
//  [ 'third rank item' ],
//  [ 'third rank item' ],
//  [ 'third rank item' ] ]

이렇게 된다는 말임

 

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