javascript - How can I pass a parameter to callback function which is inside map function

Question

I am a new learner of JS, there is a function like this

const generateNum = (array, key) => {
    return array.map(i => parseFloat(i.key));
}

however, in this fn, key is declared but never used, how can I pass this parameter to the inside of map fn. Many thanks

question from:https://stackoverflow.com/questions/65599246/how-can-i-pass-a-parameter-to-callback-function-which-is-inside-map-function

Answer 1

const generateNum = (array, key) => {
  return array.map(i => parseFloat(i[key]));
}

A simple example for explanation.

let person = {
  name: 'John',
  age: 30,
};

let key = 'name';

person.key; // does not exist (only name and age is inside person object) so it would be undefined
person[key]; // exists because it means person.name actually