Hello @CharanKulukuri ,
Modify and add these lines of code as per requirement

function onChange(control, oldValue, newValue, isLoading) {
   if (isLoading || newValue == '') {
      return;
   }
	var title=this.document.getElementById("sp_formfield_text");
	if(newValue=="1")
	{
		title.style.backgroundColor="blue";
	}
	else
	{
			title.style.backgroundColor="red";
	}
}

// here Element ID is "sp_formfield_+VariableName". 
//Prefix "sp_formfield_" is  concatenated
//if variable name is subnet_retrieved then element ID is "sp_formfield_subnet_retrieved"

As mentioned by @Ankur Bawiskar DOM manipulation can cause scripts to break or generate unexpected errors especially after platform upgrades.