PageDown Headings that support H1-H4

PageDown Headings that support H1-H4

//replace this method
commandProto.doHeading = function (chunk, postProcessing) {
    // Remove leading/trailing whitespace and reduce internal spaces to single spaces.
    chunk.selection = chunk.selection.replace(/\s+/g, " ");
    chunk.selection = chunk.selection.replace(/(^\s+|\s+$)/g, "");

    // If we clicked the button with no selected text, we just
    // make a level 2 hash header around some default text.
    if (!chunk.selection) {
        chunk.startTag = "#### "; /* rewrite to start at H4 instead */
        chunk.selection = this.getString("headingexample");
        chunk.endTag = "\n";
        return;
    }

    var headerLevel = 0;     // The existing header level of the selected text.

    // Remove any existing hash heading markdown and save the header level.
    chunk.findTags(/#+[ ]*/, /[ ]*#+/);
    if (/#+/.test(chunk.startTag)) {
        headerLevel = re.lastMatch.length;
    }
    chunk.startTag = chunk.endTag = "";

    // Try to get the current header level by looking for - and = in the line
    // below the selection.
    chunk.findTags(null, /\s?(-+|=+)/);
    if (/=+/.test(chunk.endTag)) {
        headerLevel = 1;
    }
    if (/-+/.test(chunk.endTag)) {
        headerLevel = 2;
    }

    /* not using ---- or ==== so no need to skip a line

    // Skip to the next line so we can create the header markdown.
    chunk.startTag = chunk.endTag = "";
    chunk.skipLines(1, 1);
        */

    // We make a level 2 header if there is no current header.
    // If there is a header level, we substract one from the header level.
    // If it's already a level 1 header, it's removed.
    var headerLevelToCreate = headerLevel == 0 ? 4 : headerLevel - 1; /* rewrite to start at H4 instead */

    /* old
    if (headerLevelToCreate > 0) {

        // The button only creates level 1 and 2 underline headers.
        // Why not have it iterate over hash header levels?  Wouldn't that be easier and cleaner?
        var headerChar = headerLevelToCreate >= 2 ? "-" : "=";
        var len = chunk.selection.length;
        if (len > SETTINGS.lineLength) {
            len = SETTINGS.lineLength;
        }
        chunk.endTag = "\n";
        while (len--) {
            chunk.endTag += headerChar;
        }
    }
    */

    if (headerLevelToCreate > 0) {
        var hashesToCreate = headerLevelToCreate;

        while (hashesToCreate--) {
            chunk.startTag += "#";
        }
        chunk.startTag += " "; //So we have #### Header instead of ####Header (optional)
    }
};