Convert JavaScript array of 2 element arrays into object key value pairs

Question

What is the fastest algorithm for getting from something like this:

var array = [ [1,\'a\'], [2,\'b\'], [3,\'c\'] ];

to something like this

Answer 1

Terse version using modern syntax:

let objectify = a => a.reduce( (o,[k,v]) => (o[k]=v,o), {} );

I use this technique as part of a terse query string parser:

// Converts "?foo=bar&j=1&go" into { foo:'bar', j:'1', go:true }
function parseQueryString(qs) {
    var q = decodeURIComponent;
    return qs.replace(/^\?/,'').split('&').map(s => s.split('='))
             .reduce((o,[k,v]) => (o[q(k)] = v?q(v):true, o), {});
}