Firefox扩展：如何填充输入文本字段

Question

I have a custom toolbar button created in accordance with the tutorial . The javascript code for the button is the following:

CustomButton = {

1: function () {
  alert("Just testing") 
  },

}

And it works. When I click on this button, alert happens. I'm trying to make some changes, namely, fill input field on clicking this button, but this piece of code doesn't work:

CustomButton = {

1: function () {
  document.getElementById("loginUserName").value = "aaaa";  
  },

}

The element with Id "loginUserName" exists on the page. I can easily fill it with Selenium WebDriver:

driver.findElement(By.id("loginUserName")).sendKeys(User). 

So my question is why it doesn't work in Firefox extension?

Thanks, Racoon

Answer 1

Your toolbar button and the input field (assuming the latter is part of a web page) live in separate documents. But it's easy cross the boundary. Change your code to

gBrowser.contentDocument.getElementById("loginUserName").value = "aaaa";