JavaScript doubt: clutter array with loop

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JavaScript doubt: clutter array with loop

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I am doing an exercise for a job and I have a problem when messing an array. That is, I have an array called "numbers" and a function that messes up. Then I create an empty array called "disordered numbers" which I will fill with three positions, which will be three times the array "numbers" messed up differently. Why when I create the positions of the array "disordered numbers" with the function of cluttering the "numbers" array, does it always create the same clutter? I show you code and the result:

function desordenar(array){
  array = array.sort(function() {return Math.random() - 0.5});
  return array;
} // esta función me desordena un array

var numeros= ["1", "2", "3", "4", "5"]; //este es mi array

numerosDesordenados= []; // array vacio

for (i=0;i<3;i++){ //creo bucle para llenar array vacío
  numerosDesordenados[i] = desordenar(numeros);
}

If I do a console.log(numeros) it shows me in console ["1, "2", "3", "4", "5"] . Well ... If I do a console.log(numerosDesordenados) it shows me an array with three positions always with the same mixture, for example:

[0] = ["2","3","1","5","4"]

[1] = ["2","3","1","5","4"]

[3] = ["2","3","1","5","4"]

I want the three positions to be different. How can I do it?? Thank you very much!

java javascript array script

asked by Miyūki Chiryoku 12.05.2018 в 18:15

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1 answer

Periodicity of a list in Haskell Duplicate similar objects to contain different data?

score 1 · Accepted Answer

This happens because arrays in javascript are objects and variables are references to those objects, so when assigning from variable to variable it is the same object that is referenced / changed.

One way to make a "copy" of an array in a new object is with the propagation operator (spread syntax) that "expands" the array and so the elements in brackets create a new array: [... array ]

function desordenar(unArray){
  var t = unArray.sort(function(a,b) {return (Math.random()-0.5)});
  return [...t];
} // esta función me desordena un array

var numeros= ["1", "2", "3", "4", "5"]; //este es mi array

numerosDesordenados= []; // array vacio

for (i=0;i<3;i++){ //creo bucle para llenar array vacío
  x = desordenar(numeros);
  numerosDesordenados[i] = x;
  console.log(i,x);
}

console.log(numerosDesordenados);

note: I use the x within the loop just to make a log next to i

link

In the expression return [...t]; the "ellipsis" is the operador de propagación that what it does is take the elements of t and propagate them, or scatter them separated with commas, as this occurs inside the square brackets, the result is a new array.