example.js

function smartify(info, tab) {
    var selection = info.selectionText;
    var words = selection.split(/\b/);
    var word;
    for (var i = 0; i < words.length; i++) {
        word = words[i].toLowerCase();
        if (word === 'joey') {
            words[i] = 'baby kangaroo';
        } else if (word === 'heart') {
            words[i] = 'full sized aortic pump';
        } else if (word === 'hearts') {
            words[i] = 'full sized aortic pumps';
        }
    }
    selection = words.join('');
    var range = window.getSelection().getRangeAt(0);
    range.deleteContents();
    range.insertNode(document.createTextNode(selection));
    console.log(selection);
}

// Globals
var globalChance = .1;
var semiColonChance = globalChance;

// Takes a word and the 'smartified' word and returns the smartified word in the correct casing.
// This only cares about the first letter of the word
// Input: word : string, smartified: string
// Output: string
function properCase(word, smartified) {
    if (word[0].toUpperCase() === word[0]) { // If first letter is capital
        return (smartified[0].toUpperCase() + smartified.substring(1, smartified.length)); // Return with first letter capital
    }
    return smartified; // Otherwise return as normal
}

// Takes a word and returns a supposed synonym from a thesaurus
// Input: word : string
// Output: string
function thesaurus(word) {
    return word;
}

// Takes a single word and 'smartifies' it
// Input: word: string
// Output: string
function translateWord(word) {
    // Special Cases
    if (/\bjoey\b/i.test(word)) { // We're dealing with Joey
        return properCase(word, 'baby kangaroo');
    } else if (/\bheart\b/i.test(word)) {
        return properCase(word, 'full-sized aortic pump');
    } else if (/\bhearts\b/i.test(word)) {
        return properCase(word, 'full-sized aortic pumps');
    }
    return thesaurus(word);
}

// Takes a single token and 'smartifies' it
// Input: token: string
// Output: string
function translateSingle(token) {
    var i;
    if (/\w/.test(token)) { // Dealing with a word
        return translateWord(token);
    } else if (i = /,/.exec(token)) { // sometimes replace ',' with ';'
        if (Math.random() < semiColonChance) {
            token = token.substring(0, i.index) + ';' +  token.substring(i.index + 1, token.length);
        }
    }
    return token; // Otherwise leave unpermuted
}

// Takes a paragraph/grouping of words and 'smartifies' it
// Input: text: string
// Output: string
function translateParagraph(text) {
    text = text.split(/\b/);
    for (var i = 0; i < text.length; i++) {
        text[i] = translateSingle(text[i]);
    }
    return text.join('');
}

// top level, simple replaces the info
// Input: info
//        tab
function smartify(info, tab) {

    var returnText = translateParagraph(info.selectionText);

}