Split number into 4 random numbers

function get4() {

    function iter(temp) {
        return function (v) {
            var t = temp.concat(v);
            if (t.length === 4) {
                if (t.reduce(add) === 10) {
                    result.push(t);
                }
                return;
            }
            values.forEach(iter(t));
        };
    }
    
    const
        add = (a, b) => a + b,
        values = [1, 2, 3, 4],
        result = [];

    values.forEach(iter([]));
    return result;
}

console.log(get4().map(a => a.join(' ')));

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function getRandom(min, max, length, sum) {
    return Array.from(
        { length },
        (_, i) => {
            var smin = (length - i - 1) * min,
                smax = (length - i - 1) * max,
                offset = Math.max(sum - smax, min),
                random = 1 + Math.min(sum - offset, max - offset, sum - smin - min),
                value = Math.floor(Math.random() * random + offset);

            sum -= value;
            return value;
        }
    );
}

console.log(Array.from({ length: 10 }, _ => getRandom(1, 4, 4, 10).join(' ')));

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const len = 4;
const total = 10;
const max = 4;

let arr = new Array(len);
let sum = 0;
do {
  // get some random numbers
  for (let i = 0; i < len; i++) {
    arr[i] = Math.random();
  }
  // get the total of the random numbers
  sum = arr.reduce((acc, val) => acc + val, 0);
  // compute the scale to use on the numbers
  const scale = (total - len) / sum;
  // scale the array
  arr = arr.map(val => Math.min(max, Math.round(val * scale) + 1));
  // re-compute the sum
  sum = arr.reduce((acc, val) => acc + val, 0);
  // loop if the sum is not exactly the expected total due to scale rounding effects
} while (sum - total);

console.log(arr);

function randomNumber(max, min) {
  while (true) {
    var r = Math.round(Math.random() * max);
    if (r >= min) {
      return r;
    }
  }
}

function splitXintoYComponentsBetweenMaxAndMin(numberToSplit, numberOfSplits, maxValue, minValue, onUpdate) {
  if (minValue === void 0) {
    minValue = 1;
  }
  //Test that a result can exist
  if (maxValue * numberOfSplits < numberToSplit || minValue * numberOfSplits > numberToSplit) {
    return new Promise(function(resolve, reject) {
      resolve(false);
    });
  }
  //Create returner array
  var arr = [];
  var accumulator = 0;
  while (arr.length < numberOfSplits) {
    var val = randomNumber(Math.floor(numberToSplit / numberOfSplits), minValue);
    accumulator += val;
    arr.push(val);
  }
  return new Promise(function(resolve, reject) {
    function runTest() {
      var d = Date.now();
      var localMaxValue = Math.min(maxValue, Math.ceil((numberToSplit - accumulator) / 4));
      //Combination loop
      while (accumulator < numberToSplit && Date.now() - d < 17) {
        var index = Math.round(Math.random() * (arr.length - 1));
        if (arr[index] >= maxValue) {
          continue;
        }
        var r = randomNumber(localMaxValue, minValue);
        while (arr[index] + r > maxValue || accumulator + r > numberToSplit) {
          if (Date.now() - d >= 17) {
            break;
          }
          r = randomNumber(localMaxValue, minValue);
        }
        if (arr[index] + r > maxValue || accumulator + r > numberToSplit) {
          continue;
        }
        arr[index] += r;
        accumulator += r;
      }
      if (accumulator < numberToSplit) {
        if (onUpdate !== void 0) {
          onUpdate(arr);
        }
        requestAnimationFrame(runTest);
      } else {
        resolve(arr);
      }
    }
    runTest();
  });
}
//TEST
var table = document.body.appendChild(document.createElement('table'));
table.innerHTML = "<thead><tr><th>Number to split</th><th>Number of splits</th><th>Max value</th><th>Min value</th><th>Run</th></tr></thead>" +
  "<tbody><tr><th><input id=\"number-to-split\" value=\"10\" type=\"number\" min=\"1\"/></th><th><input id=\"number-of-splits\" value=\"4\" type=\"number\" min=\"1\"/></th><th><input id=\"max-value\" type=\"number\" min=\"1\" value=\"4\"/></th><th><input id=\"min-value\" type=\"number\" min=\"1\" value=\"1\"/></th><th><input id=\"run\" type=\"button\" value=\"Run\"/></th></tr></tbody>";
var output = document.body.appendChild(document.createElement('pre'));
output.style.overflowX = "scroll";
document.getElementById("run").onclick = function() {
  splitXintoYComponentsBetweenMaxAndMin(parseInt(document.getElementById("number-to-split").value, 10), parseInt(document.getElementById("number-of-splits").value, 10), parseInt(document.getElementById("max-value").value, 10), parseInt(document.getElementById("min-value").value, 10))
    .then(function(data) {
      if (data !== false) {
        output.textContent += data.join("\t") + '\n';
      } else {
        output.textContent += 'Invalid data\n';
      }
    });
};