I am trying to create a site that will allow you to type a sentence or passage of text, then click on words to bring up a list of synonyms (from an online API) and possibly authorized abbreviations from a list that I provide, then once clicked on it would replace that word with the word that was clicked on. It would function kind of like After the Deadline or a Javascript based spell checker. Are there any libraries set up to make something like this easy, or what kind of Javascript do I need to be looking at? Are there any tutorials or examples for this kind of thing? I am aware that the source code for After the Deadline is available, but I only need a small portion of their technology, not all of the actual grammar and spelling check technology.

I am trying to create a site that will allow you to type a sentence or passage of text, then click on words to bring up a list of synonyms (from an online API) and possibly authorized abbreviations from a list that I provide. Once clicked, it would replace that word with the word that was clicked on. It would function kind of like After the Deadline or a Javascript based spell checker. 

Are there any libraries set up to make something like this easy, or what kind of Javascript do I need to be looking at? Are there any tutorials or examples for this kind of thing? I am aware that the source code for After the Deadline is available, but I only need a small portion of their technology, not all of the actual grammar and spelling check technology.