Invalid Quantifier

I’m having some trouble with my regualr expression. I have a search and replace script, but when I search for ? I get an invalid quantifier in the error console.

[code=html]
function search_and_replace(search_text, replace_text)
{

var text_area = document.getElementById(“ta”).value;
var str = search_text;
var reg = new RegExp(“\b” + search_text + “\b”, “gi” );
var replStr = replace_text;
document.getElementById(“ta”).value = text_area.replace(reg,replStr);

}
[/code]

How can I fix this problem?

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