this.strreplace = function(searchstr,replacestr){
        var ind = this.value.indexOf(searchstr);
        var newstr="";
        var temp = replacestr;
        var lastind = ind + searchstr.length;
        for(var i =0;i<ind;i++)
            newstr+=this.value[i];
        newstr += replacestr;
        for(var j = lastind;j<this.strlen;j++)
            newstr+= this.value[j];
        return newstr;
    }