JS round value to 2 decimal places within a message/pop up

I have been working on a project and found an error with a JS message in the UI. The number is not being rounded before being displayed. I don’t know JS very well however, I did try Math.round(num * 100) / 100 this did not work.

Any support with this would be great.

if($change_return_val != "0.00"){
                                        // confirm('Oops amount is over.');
                                        // calculate_balance_due();
                                        swal({
                                            title: "Change: £"+$change_return_val,
                                            text: "Your change return value is: £"+$change_return_val,
                                            
                                        })
                                    }

Change return message in UI

>Solution :

When converting a number to a string with a specified number of floating points, as @Ameer has said in a comment the toFixed function is the typical way to go. However, for the specific task of displaying a number as currency, you may want to consider using toLocaleString instead.

For example, this converts the number into British English style, specifically as the currency of Great British Pounds:

const numberRaw = 123.456789;
const numberCurrency = numberRaw.toLocaleString('en-GB', { style: 'currency', currency: 'GBP' });

console.log(numberCurrency);

This method is also particularly useful if you have to deal with many locales, some of which may display numbers in quite different ways such as '1.234,57'.