Definition for divMod() in JavaScript. Differs from python's version due to how modulo is defined by the language.

python-style-divmod.js

function divmod(a, b) {
  var remainder = a % b;
  var aIsInfinite = a === -Infinity || a === Infinity;
  var bIsInfinite = b === -Infinity || b === Infinity;
  var aIsNeg = a + 1 / a < 0;
  var bIsNeg = b + 1 / b < 0;
  return [
    (aIsInfinite !== bIsInfinite && a) ? aIsInfinite ? NaN : aIsNeg === bIsNeg ? 0 : -1 : Math.floor(a / b),
    (!a && b < 0) ? -0 : remainder + (remainder !== 0 && aIsNeg !== bIsNeg ? b : 0)
  ];
}

YourJS.divMod.js

function divMod(a, b) {
  return [Math.trunc(a / b), a % b];
}

~test-python-style-divmod.js

// HIDE \\
console.load('local://python-style-divmod.js');

// HIDE \\
function isSameNumber(a, b) {
  return a === 0
    ? 1 / a === 1 / b
    : (a === b || (Number.isNaN(a) && Number.isNaN(b)));
}

function pyStr(value) {
  return value === Infinity
    ? "float('inf')"
    : value === -Infinity
      ? "-float('inf')"
      : Number.isNaN(value)
        ? "float('nan')"
        : str(value).replace(/^-?\d+$/, '$&.0');
}

function str(value) {
  return value === 0 ? 1 / value < 0 ? '-0' : '0' : value + '';
}

var tests = [
  [-Infinity, -Infinity, NaN, NaN],
  [-Infinity, -7, NaN, NaN],
  [-Infinity, -6.5, NaN, NaN],
  [-Infinity, -3, NaN, NaN],
  [-Infinity, 3, NaN, NaN],
  [-Infinity, 6.5, NaN, NaN],
  [-Infinity, 7, NaN, NaN],
  [-Infinity, Infinity, NaN, NaN],
  [-7, -Infinity, 0.0, -7.0],
  [-7, -7, 1, 0],
  [-7, -6.5, 1.0, -0.5],
  [-7, -3, 2, -1],
  [-7, 3, -3, 2],
  [-7, 6.5, -2.0, 6.0],
  [-7, 7, -1, 0],
  [-7, Infinity, -1.0, Infinity],
  [-4.5, -Infinity, 0.0, -4.5],
  [-4.5, -7, 0.0, -4.5],
  [-4.5, -6.5, 0.0, -4.5],
  [-4.5, -3, 1.0, -1.5],
  [-4.5, 3, -2.0, 1.5],
  [-4.5, 6.5, -1.0, 2.0],
  [-4.5, 7, -1.0, 2.5],
  [-4.5, Infinity, -1.0, Infinity],
  [-0.0, -Infinity, 0.0, -0.0],
  [-0.0, -7, 0.0, -0.0],
  [-0.0, -6.5, 0.0, -0.0],
  [-0.0, -3, 0.0, -0.0],
  [-0.0, 3, -0.0, 0.0],
  [-0.0, 6.5, -0.0, 0.0],
  [-0.0, 7, -0.0, 0.0],
  [-0.0, Infinity, -0.0, 0.0],
  [0.0, -Infinity, -0.0, -0.0],
  [0.0, -7, -0.0, -0.0],
  [0.0, -6.5, -0.0, -0.0],
  [0.0, -3, -0.0, -0.0],
  [0.0, 3, 0.0, 0.0],
  [0.0, 6.5, 0.0, 0.0],
  [0.0, 7, 0.0, 0.0],
  [0.0, Infinity, 0.0, 0.0],
  [4.5, -Infinity, -1.0, -Infinity],
  [4.5, -7, -1.0, -2.5],
  [4.5, -6.5, -1.0, -2.0],
  [4.5, -3, -2.0, -1.5],
  [4.5, 3, 1.0, 1.5],
  [4.5, 6.5, 0.0, 4.5],
  [4.5, 7, 0.0, 4.5],
  [4.5, Infinity, 0.0, 4.5],
  [7, -Infinity, -1.0, -Infinity],
  [7, -7, -1, 0],
  [7, -6.5, -2.0, -6.0],
  [7, -3, -3, -2],
  [7, 3, 2, 1],
  [7, 6.5, 1.0, 0.5],
  [7, 7, 1, 0],
  [7, Infinity, 0.0, 7.0],
  [Infinity, -Infinity, NaN, NaN],
  [Infinity, -7, NaN, NaN],
  [Infinity, -6.5, NaN, NaN],
  [Infinity, -3, NaN, NaN],
  [Infinity, 3, NaN, NaN],
  [Infinity, 6.5, NaN, NaN],
  [Infinity, 7, NaN, NaN],
  [Infinity, Infinity, NaN, NaN]
];

//\\
tests.forEach(function(values, index) {
  var a = values[0];
  var b = values[1];
  var e0 = values[2];
  var e1 = values[3];
  var results = divmod(a, b);
  var r0 = results[0];
  var r1 = results[1];
  var expr = 'Python: divmod(' + pyStr(a) + ', ' + pyStr(b) + ') \u21E8 (' + pyStr(e0) + ', ' + pyStr(e1) + ')';
  var rExpr = '[' + str(r0) + ', ' + str(r1) + '] \u21E6 JS: divmod(' + str(a) + ', ' + str(b) + ')';
  var isRight = isSameNumber(e0, r0) && isSameNumber(e1, r1);
  console[isRight ? 'log' : 'error']('(' + (index + 1) + ')\t' + expr + (isRight ? ' = ' : ' \u2260 ') + rExpr);
});

Testing the Python-style divmod() function:
https://www.yourjs.com/console/?gist=85320e5d7e7788cb114a57fc19394632&file=~test-python-style-divmod.js&skipIntro=1