const powerset = (array) => {
  const result = [[]];
 
  const arrayPower = Math.pow(2, array.length);
  for (let index = 1; index < arrayPower; ++index){
    const subset = [];
    for (let i = 0; i < array.length; i++){
      const subsetPower = Math.pow(2, i);
      if (index & subsetPower){
        subset.push(array[i]);
      }
    }
 
    result.push(subset);
  }
 
  return result;
};
 
for(const set of powerset([1,2,3])) console.log(`subset: ${set}`);

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