In case you want your dtr array to be the first array in the 2d array. One could do this:
var a = ['s','s','n'];
var b = [[50, 50, 50],
[50 , 5, 5],
['hello', 'beta', 'gama']];
var result = [a].concat(b);
Result:
[['s','s','n'],
[50, 50, 50],
[50 , 5, 5],
['hello', 'beta', 'gama']];
Edit
var a = ['s','s','n'];
var b = [[50, 50, 'hello'],
[50, 5, 'beta'],
[50, 5, 'gama']];
var result = _.map(_.zip(a, b), _.flatten)
// if native map support _.zip(a, b).map(_.flatten)
Result:
[['s', 50, 50, 'hello'],
['s', 50, 5, 'beta'],
['n', 50, 5, 'gama']];