no-magic-numbers ignore calculations

I have a const like const oneDay = 1000 * 60 * 60 * 24; With "no-magic-numbers": [2, { ignore: [1000] }]" No magic number: 60 [no-magic-numbers] const oneDay = 1000 * 60 * 60 * 24;`

The point of doing the oneDay was to not have a magic number/calculation, would it be possible to add an option to ignore magic numbers that are directly behind an assignment?

[IanVS]

The number of milliseconds in a day is a constant (ignoring leap seconds), so just create it as a constant. Why do you need to make the computer do your math for you? You can explain with a comment if you really feel the need.

const millisecondsPerDay = 86400000; // 24 * 60 * 60 * 1000

[keithamus]

I would request this rule for instances where a simple calculation is needed. Take for example the following code:

const myArray = [1,2,3];
const lastIndex = myArray.length - 1;

This const uses 1 number as part of the calculation, and should be allowed to be passed through - because the number on its own has no semantic value, and trying to give it a useful name becomes a struggle, e.g:

const myArray = [1,2,3];
const lastIndexLengthDelta = 1;
const lastIndex = myArray.length - lastIndexLengthDelta;

I’d argue the first example, while not attaching a semantic value to the number, is more readable than the 2nd. Thoughts?

BTW to better clarify my stance: I get that I can just whitelist the number 1 - but I think it would be even better have the option of a threshold of numbers used in a calculation. E.g.

/* eslint no-magic-numbers: 2 { "numbersAllowedInCalculations": 0 } */
const lastIndex = myArray.length - 1; // errors

/* eslint no-magic-numbers: 2 { "numbersAllowedInCalculations": 1 } */
const lastIndex = myArray.length - 1; // does not error