leastDistance.js

function leastDistance(input) {
  const rowDim = input[0].length
  const colDim = input.length
  const isValidInput = !input.find(r => r.length !== rowDim)
  
  // Track all positions for 1 and 2s;
  // the 1 will be the first element
  const positions = []
  input.forEach((row, i) => {
  	Array.from(row).forEach((s, j) => {
  		// If it's a 1, then add it at the beggining
  		// of `positions`
  		// Comparison to int, thanks to (==) JS :)
  		if (s == 1) {
  			positions.unshift([i, j])
  		} 
  		if (s == 2) {
  			positions.push([i, j])
  		}
  		
  	})
  })

  // Now find the least distance
  const onePos = positions.shift()
  return positions.reduce((min, twoPos) => {
  	const downWise = Math.abs(twoPos[0]-onePos[0])
  	const upWise = colDim - downWise
  	const rightWise = Math.abs(twoPos[1]-onePos[1])
  	const leftWise = rowDim - rightWise

  	return Math.min(
  		min,
  		Math.min(
  			upWise + rightWise,
  			upWise + leftWise,
  			downWise + rightWise,
  			downWise + leftWise,
  		)
  	)
  }, Infinity)
}

The problem of this code is that it's always expecting to find at least one instance of 1 and 2, while it should return 0 on some conditions

Input may be expressed as strings
e.g.

const input = [
	"00000",
	"00020",
	"00000",
	"00100",
]