Javascript - sort array based on another array

One-Line answer.

itemsArray.sort(function(a, b){  
  return sortingArr.indexOf(a) - sortingArr.indexOf(b);
});

Or even shorter:

itemsArray.sort((a, b) => sortingArr.indexOf(a) - sortingArr.indexOf(b));

Something like:

items = [ 
    ['Anne', 'a'],
    ['Bob', 'b'],
    ['Henry', 'b'],
    ['Andrew', 'd'],
    ['Jason', 'c'],
    ['Thomas', 'b']
]

sorting = [ 'b', 'c', 'b', 'b', 'c', 'd' ];
result = []

sorting.forEach(function(key) {
    var found = false;
    items = items.filter(function(item) {
        if(!found && item[1] == key) {
            result.push(item);
            found = true;
            return false;
        } else 
            return true;
    })
})

result.forEach(function(item) {
    document.writeln(item[0]) /// Bob Jason Henry Thomas Andrew
})

Here's a shorter code, but it destroys the sorting array:

result = items.map(function(item) {
    var n = sorting.indexOf(item[1]);
    sorting[n] = '';
    return [n, item]
}).sort().map(function(j) { return j[1] })

If you use the native array sort function, you can pass in a custom comparator to be used when sorting the array. The comparator should return a negative number if the first value is less than the second, zero if they're equal, and a positive number if the first value is greater.

So if I understand the example you're giving correctly, you could do something like:

function sortFunc(a, b) {
  var sortingArr = [ 'b', 'c', 'b', 'b', 'c', 'd' ];
  return sortingArr.indexOf(a[1]) - sortingArr.indexOf(b[1]);
}

itemsArray.sort(sortFunc);