preserve NPM version

Temporarily substitute tokens in the given string with placeholders, then put them back after transforming the string.

Useful for protecting tokens, like templates in HTML, from being mutated when the string is transformed in some way, like from a formatter/beautifier.

Example without preserve

Let’s say you want to use js-beautify on a string of html with Lo-Dash/Underscore templates, such as: <ul><li><%= name %></li></ul>:

js-beautify will render the template unusable (and apply incorrect formatting because of the unfamiliar syntax from the Lo-Dash template):

    <%=n ame %>

Example with preserve


  <li><%= name %></li>

For the record, this is just a random example, I’ve had very few issues with js-beautify in general. But with or without js-beautify, this kind of token mangling does happen sometimes when you use formatters, beautifiers or similar tools.


Install with npm

npm i preserve --save

Run tests

npm test



Replace tokens in str with a temporary, heuristic placeholder.

//=> '{__ID1__}'


Replace placeholders in str with original tokens.

//=> '{a\\,b}'


Pull requests and stars are always welcome. For bugs and feature requests, please create an issue


Jon Schlinkert


Copyright (c) 2015-2015, Jon Schlinkert. Released under the MIT license

This file was generated by verb on January 10, 2015.