get individual digits of

Benchmark created on

Description

"what are the decimal digits of 𝑛 ∈ β„•" "figure it out with Math.ceil(Math.log(𝑛)) or String(𝑛).length" "which is...... faster" c.f. https://jsperf.app/gorehi for just getting the length itself

Setup

// only works if JS doesn't sciencify the string 
// representation for large values (X.XXXe+X)
// so like... 𝑛 < 10Β²ΒΉ or so?
const L = 10e20;
function test (digitsOfN) {
	let 𝑛 = 100;
	while ((𝑛 *= 1.19) < L) digitsOfN(𝑛);
}

Test runner

Ready to run.

Testing in
TestOps/sec
get the digits of 𝑛 using 𝕸𝖆𝖙𝖍 β‘ 
// goes left to right shaving off the leading digit
test(n => {
  let l = Math.ceil(Math.log10(n))
  const d = [];
  while (l--) {
  	const m = (10**l);
  	d.push(Math.trunc(n / m))
  	n = n % m;
  }
  return d;
});
ready
get the digits of 𝑛 using 𝓒𝓽𝓻𝓲𝓷𝓰
test(n => Array.from(String(n), Number));
ready
get the digits of 𝑛 using 𝕸𝖆𝖙𝖍 β‘‘
// goes right to left shaving off the last digit
test(n => {
  const d = [];
  while (n) {
  	const l = n % 10;
  	n = (n - l) / 10
  	d.unshift(l);
  }
  return d;
});
ready
get the digits of 𝑛 using 𝕸𝖆𝖙𝖍 β‘’
// goes right to left shaving off the last digit
// (assembles in reverse then flips the array)
test(n => {
  const d = [];
  while (n) {
  	const l = n % 10;
  	n = (n - l) / 10
  	d.push(l);
  }
  return d.reverse();
});
ready
get the digits of 𝑛 using 𝕸𝖆𝖙𝖍 β‘£
// goes right to left shaving off the last digit
// (trying optimizations)
test(n => {
  const d = [];
  while (n) {
  	d.unshift(n % 10);
  	n = Math.trunc(n / 10)

  }
  return d;
});
ready
get the digits of 𝑛 using 𝕸𝖆𝖙𝖍 β‘€
// goes right to left shaving off the last digit
// (assembles in reverse then flips the array)
// (trying optimizations)
test(n => {
  const d = [];
  while (n) {
  	d.push(n % 10);
  	n = Math.trunc(n / 10)
  }
  return d.reverse();
});
ready

Revisions

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