fairlyDeepClone ...

fairlyDeepClone.js

//b = JSON.parse(JSON.stringify(a));

function fairlyDeepClone(o) {
    if (Array.isArray(o)) {
        // handle array
        return o.map(function(i) {
            return fairlyDeepClone(i);
        });
    } else if (typeof o === 'object') {
        // handle object
        var oo = {};
        Object.keys(o).forEach(function(k) {
           oo[k] = fairlyDeepClone(o[k]); 
        });
        return oo;
    } else {
        return o;
    }
}

a = [ [ 1, 2 ], { '3': [ 4, 5 ] }, 9, 'ten' ];
b = fairlyDeepClone(a);