RegEx not matching correctly when using new RegExp

Question

I am trying to use regex to match a letter against strings and then using test however, it doesn't always match a letter with every string.

    x = [
    'Mike',
    'Mary',
    'Bob',
    'Julie',
    'Jon',
    'Adam'
];

Working: (not using new RegExp)

x.map(function(a) { console.log(a, /(m)/ig.test(a)); });
VM745:2 Mike true
VM745:2 Mary true
VM745:2 Bob false
VM745:2 Julie false
VM745:2 Jon false
VM745:2 Adam true 

Not working: (using new RegExp)

y = new RegExp('(m)', 'ig');
       x.map(function(a) { console.log(a, y.test(a)); });
VM748:2 Mike true
VM748:2 Mary false
VM748:2 Bob false
VM748:2 Julie false
VM748:2 Jon false
VM748:2 Adam true