var expression = /[-a-zA-Z0-9@:%._+~#=]{1,256}.[a-zA-Z0-9()]{1,6}([-a-zA-Z0-9()@:%_+.~#?&//=]*)?/gi;
var regex = new RegExp(expression);
var t = 'www.google.com';
if (t.match(regex)) {
alert("Successful match");
} else {
alert("No match");
}
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