How to capitalize first letter of each word, like a 2-word city? [duplicate]

My JS woks well when the city has one word:

• cHIcaGO ==> Chicago

But when it's

• san diego ==> San diego

How do I make it become San Diego?

function convert_case() {
    document.profile_form.city.value =
        document.profile_form.city.value.substr(0,1).toUpperCase() + 
        document.profile_form.city.value.substr(1).toLowerCase();
}

There's a good answer here:

function toTitleCase(str) {
    return str.replace(/\w\S*/g, function(txt){
        return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    });
}

or in ES6:

var text = "foo bar loo zoo moo";
text = text.toLowerCase()
    .split(' ')
    .map((s) => s.charAt(0).toUpperCase() + s.substring(1))
    .join(' ');

You can use CSS:

p.capitalize {text-transform:capitalize;}

Update (JS Solution):

Based on Kamal Reddy's comment:

document.getElementById("myP").style.textTransform = "capitalize";

function convertCase(str) {
  var lower = String(str).toLowerCase();
  return lower.replace(/(^| )(\w)/g, function(x) {
    return x.toUpperCase();
  });
}