Precision-Random.js

// Maybe the easiest way => play with dot
// issue!!! => the float after 5 are all token by 5?
/*
function grabRandomDotWay(min, max, toNthDecimals) {
	let result = null;
	const range = max - min;
	result = Math.trunc((range + 1) * Math.random() * (toNthDecimals && (Math.pow(10, toNthDecimals)) || 1));
	// eg : result *= 0.01
	result = result * Math.pow(0.1, toNthDecimals || 0) + '';
	if (toNthDecimals) {
		result>range&&(result = `${range}`);
		return result.slice(0, result.indexOf('.') - 0 + toNthDecimals + 1) - 0 + min;
	} else {
		return Math.trunc(result);
	}
}
*/
/* here is the improvement version */
function grabRandomDotWay(min, max, toNthDecimals) {
  if (toNthDecimals) {
    let result = null
    const range = max - min
    result = Math.trunc(
      range *
        Math.random() *
        ((toNthDecimals && Math.pow(10, toNthDecimals)) || 1)
    )
    // eg : result *= 0.01
    result = result * Math.pow(0.1, toNthDecimals || 0) + ''
    result > range - Math.pow(0.1, toNthDecimals) && (result = `${range}`)
    return (
      result.slice(0, result.indexOf('.') - 0 + toNthDecimals + 1) - 0 + min
    )
  } else {
    return Math.trunc((range + 1) * Math.random())
  }
}

// Math.trunc
function grabRandomTrunc(min, max, toNthDecimals = 0) {
  const range = max - min
  let result = (range * Math.random()).toString()
  if (toNthDecimals) {
    let replaceNum = null
    const index = result.indexOf('.') - 0 + toNthDecimals
    replaceNum = Math.trunc(('0.' + result.slice(index) - 0) * 11)

    if (replaceNum >= 10) {
      result = Number(result)
      toNthDecimals === 1
        ? (result = result + 1)
        : (result += 0.1 * (toNthDecimals - 1))
      result = result.toString().slice(0, index + 1) - 0
    } else {
      result = Number(
        result.replace(result.charAt(index), replaceNum).slice(0, index + 1)
      )
    }
  } else {
    result = (max - min + 1) * Math.random()
    result = Math.trunc(result)
  }

  result > range && (result = range)
  return result - -min
}

// Evenly dividion
function grabRandomEvenly(min, max, toNthDecimals) {
  let result = null
  const range = max - min
  toNthDecimals || (result = Math.trunc((range + 1) * Math.random()))
  if (toNthDecimals !== 0) {
    result = (range * Math.random()).toString()
    const index = result.indexOf('.') - 0 + toNthDecimals,
      replaceNum = Math.trunc(('0.' + result.slice(index) - 0) * 11)
    if (replaceNum >= 10) {
      result += 0.1 * (toNthDecimals - 1)
      result = result.slice(0, index + 1) - 0
    } else {
      result =
        result.replace(result.charAt(index), replaceNum).slice(0, index + 1) - 0
    }
  }
  result > range && (result = range)

  return result - -min
}

// Precision test script (10000 * 999 times)
function loopCheck(c, r) {
  'use strict'
  c++
  r += (function check(c, r) {
    'use strict'
    c++
    r += grabRandomDotWay(0, 5, 3)
    if (c >= 10000) {
      c = 0
      return r / 10000
    }
    return check(c, r)
  })(1, 0)
  if (c >= 999) {
    return r / 999
  }
  return loopCheck(c, r)
}
console.log(loopCheck(1, 0))