Format the text in JavaScript alert box

Question

How can I format the text in a JavaScript alert box? I need a word in the text to be underlined.

Answer 1

Underline a string using unicode character '\u0332', called a COMBINING LOW LINE

function underline(s) {
    var arr = s.split('');
    s = arr.join('\u0332');
    if (s) s = s + '\u0332';
    return s;
}

var str = underline('hello world'); // "h̲e̲l̲l̲o̲ ̲w̲o̲r̲l̲d̲"

alert(str);

This method is not guaranteed to produce a smooth underline.

Example of confirm() on Firefox 59: