Question

I would like to move JS code snippets out of PHP files and into their own files in order to make code a lot cleaner and easier to maintain. For example, I have this function:

function load_script($fieldname)
{
  return
  'var help = function () {alert(' . '"EDITOR HELP:\n\n' . 
                                     'blah blah.\n\n' . 
                                     'more blah blah.\n\n' . 
                                     ');}' . "\n" .
  'var options = { handler: help, title: "Editor help" };' . "\n" .
  'var converter = Markdown.getSanitizingConverter();' . "\n" .
  'var editor = new Markdown.Editor(converter, "-'.$fieldname.'", options);' . "\n" .
  'editor.run();' . "\n";
}

Notice the $fieldname PHP variable.

The idea is to store the JS portion in a .js file. Then I’d read it in as plain text in order to output in the return statement. In other words, something like this:

function load_script($fieldname)
{
  $output = file_get_contents("load_script.js");
  return $output;
}

Obviously the problem is that this would not substitute $fieldname with the corresponding value.

My current thought on this is to run $output through string subsitution:

function load_script($fieldname)
{
  $output = file_get_contents("load_script.js");
  $output = str_replace("some_unique_identifier", $fieldname, $output);
  return $output;
}

Is there a better approach?

EDIT:

I should add some of the motivation behind this:

First, the example given is ugly and hard to maintain for anything but the simplest JS snippets. Lots of room for mistakes.

Second, editors aren’t very helpful in terms of checking syntax and highlighting when you mix things up this way.

Third, having JS live on its own files makes it easier to run a minification script that crunches on the entire site (so you don’t have to manually maintain minification).

Answer 1

You could use a template engine to do this (such as Smarty for instance). Simply write your JS files using the template variables where your PHP variables would be, and load them through PHP.

You could even roll your own simple one. Something like:

// in JS file:
function myFunc() {
    alert("hello %s");
}

// in PHP file:
<?PHP
    //... code to open JS file and load into string....
    echo sprintf($contentsOfJSFile, "John Doe");
?>

RESULTING OUTPUT: 

function myFunc() {
    alert("hello John Doe");
}