All generated random value is same

This is the code that I wrote, I dont know why all the 50 rgbColor generate the same value even when I wrote the random function in randomRGBValue.

var html = '';
var valueArr = [];
var rgbColor;

function randomValue() {
  for (var i = 0; i < 3; i += 1) {
    valueArr.push(Math.floor(Math.random() * 256 ));
  }
  return valueArr;
}

function randomRGB() {
  randomValue();
  var color;
  color = 'rgb(';
  color += valueArr[0] + ',';
  color += valueArr[1] + ',';
  color += valueArr[2] + ')';
  return color;
}

for (var i = 0; i < 50; i += 1) {
  rgbColor = randomRGB();
  html += '<div style="background-color:' + rgbColor + '"></div>';
}

document.write(html);

To ease understanding of my poor written code,

-> randomValue function is for generating random value from 1 to 255(3 sets) and is pushed into valueArr. valueArr is returned.

Example valueArr = (value1, value2, value3)

-> randomRGB function calls randomValue function and plugs in valueArr value into the color array.