messageName

string. The name of the message, as specified in the messages.json file. If the message can't be found in messages.json:

• Firefox returns "" and logs an error.
• Chrome returns "" and does not log an error.

substitutionsOptional

string orarray ofstring. A single substitution string, or an array of substitution strings.

In Chrome, if you supply more than 9 substitution strings,getMessage() will returnundefined.

string. Message localized for current locale.

Get the localized string for"messageContent", withtarget.url substituted:

let message = browser.i18n.getMessage("messageContent", target.url);console.log(message);

This would work with a _locales/en/messages.json file containing:

{  "messageContent": {    "message": "You clicked $URL$.",    "description": "Tells the user which link they clicked.",    "placeholders": {      "url": {        "content": "$1",        "example": "https://developer.mozilla.org"      }    }  }}

Iftarget.url is "https://developer.mozilla.org", then the value of message, in the "en" locale, would be:

"You clicked https://developer.mozilla.org."

• menu-accesskey-visible
• menu-demo
• notify-link-clicks-i18n