从pre / code标签中的缩进HTML源中删除前导空格

Question

I currently have the following html within a pre-code block:

                <pre class="prettyprint"><code>
                    &lt;html&gt;
                    &lt;body&gt;

                    &lt;form name=&quot;input&quot; action=&quot;html_form_action.asp&quot; method=&quot;get&quot;&gt;
                    &lt;input type=&quot;radio&quot; name=&quot;sex&quot; value=&quot;male&quot;&gt;Male&lt;br&gt;
                    &lt;input type=&quot;radio&quot; name=&quot;sex&quot; value=&quot;female&quot;&gt;Female&lt;br&gt;
                    &lt;input type=&quot;submit&quot; value=&quot;Submit&quot;&gt;
                    &lt;/form&gt; 

                    &lt;p&gt;If you click the &quot;Submit&quot; button, the form-data will be sent to a page called &quot;html_form_action.asp&quot;.&lt;/p&gt;

                    &lt;/body&gt;
                    &lt;/html&gt;
                </code></pre>

It is indented within the html source for better structure within the document. How can I remove the leading whitespace? Through the use of javascript or is there a more simple method.

Answer 1

The question asks if there's a JavaScript solution or a simpler method for removing leading whitespace. There's a simpler method:

CSS

pre, code {
    white-space: pre-line;
}

DEMO

white-space

The white-space property is used to describe how whitespace inside the element is handled.

pre-line

Sequences of whitespace are collapsed.

Answer 2

I really like Homam's idea, but I had to change it to deal with this:

<pre><code><!-- There's nothing on this line, so the script thinks the indentation is zero -->
    foo = bar
</code></pre>

To fix it, I just take out the first line if it's empty:

[].forEach.call(document.querySelectorAll('code'), function($code) {
    var lines = $code.textContent.split('\n');

    if (lines[0] === '')
    {
        lines.shift()
    }

    var matches;
    var indentation = (matches = /^[\s\t]+/.exec(lines[0])) !== null ? matches[0] : null;
    if (!!indentation) {
        lines = lines.map(function(line) {
            line = line.replace(indentation, '')
            return line.replace(/\t/g, '    ')
        });

        $code.textContent = lines.join('\n').trim();
    }
});

(I'm also processing <code> tags instead of <pre> tags.)

Answer 3

You may want to just change how it is output, but it is fairly simple to do with JavaScript

var p = document.querySelector(".prettyprint");
p.textContent = p.textContent.replace(/^\s+/mg, "");

http://jsfiddle.net/a4gfZ/

Answer 4

Extending the above solution, this snippet assumes the indentation of the the first line inside <pre> is 0 and it realigns all the lines based on the first line:

[].forEach.call(document.querySelectorAll('pre'), function($pre) {
  var lines = $pre.textContent.split('\n');
  var matches;
  var indentation = (matches = /^\s+/.exec(lines[0])) != null ? matches[0] : null;
  if (!!indentation) {
    lines = lines.map(function(line) {
      return line.replace(indentation, '');
    });
    return $pre.textContent = lines.join('\n').trim();
  }
});

Answer 5

When you use pre , you should format its content to be exactly as you want it to be rendered. That's the very idea of pre (preformatted text). But if it's just indentation, you could use CSS: margin-left with a suitable negative value.