How to get access_token for using chat?

Chat and IRC
10

Sorry. I didn’t understand.

Can use Only username? (not use password?)

I testing source below.(There is this source in Get started with Twitch development)
window.chatClient = new chatClient({
channel: ‘#CHANNELNAMEHERE’,
username: ‘USERNAMEHERE’,
password: ‘oauth:AUTHTOKENHERE’, <- Not use?
});