Variable determined by host name?

Is this the correct syntax?

// Determine domain used to access site
if (top.location.host.indexOf(‘.com’)) {
var DefaultURL = ‘http://www.sitename.com‘;
}
if (top.location.host.indexOf(‘.org’)) {
var DefaultURL = ‘http://www.sitename.org‘;
}

I need assign this variable based on how the site was accessed — either .org or .com. Thank you for your help!

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