Sample code to replace an ampercent symbol using Javascript.

function CorrectStringAsSPData(strValue)
{
//Replace & symbol
if(strValue)
{
var givenString=strValue.replace(/&/g,"&");

//Replace < symbol givenString=givenString.replace(/ symbol
givenString=givenString.replace(/>/g,">");

//alert(givenString)
return givenString;
}
}