javascript variables not defined in IE11 but defined in chrome

There is a namepicker which is not functioning properly in ie11 but works fine in chrome. On inspection i found that the variables are undefined in IE11 but are defined in chrome. i used the alert function in the function to test the variable.

the very 1st time i loads the page the variables are defined .On a refresh variable becomes unset.This function is called by onload in html document

function fillInitialValues()
 {

     alert("Inside fillinitialvalues ");
     alert("caller is " + arguments.callee.caller.toString());
     if (typeof isSingle !== 'undefined') {
    // the variable is defined
    alert("Variable isSingle is defined"+isSingle);
}
else
{
alert("Variable isSingle is not defined");
}

    if(!isSingle) {
        alert("Inside fillinitialvalues checking in issingle");
        targetNames = trimArray(baseTargetNames);
        alert("base target names contain "+targetNames);
        output = generateNamesHTML( targetNames, 'T' );
        writeDiv( 'target', output );
    }
    self.focus();
    document.getElementById('searchcriteria').focus();
}