String Replace Helper for Dust.js

Recently, I’ve been learning about the LinkedIn fork of Dust – a client-side templating solution. Dust allows you to create helpers, which are functions that can be called from within a rendering template. They help separate presentation from logic, which is always a good practice.

Today we created a String Replace helper, which seems like it might be pretty useful for others, so I thought I’d share it.

Following is an example of the helper in use. In this example, the replace helper will replace all instances of a period character with a hyphen in the given message string, and then it will write the trimmed result.

Usage example:

{@replace str="{message}" search="." replace="-" trim="true" /}

Here is the Replace Helper for Dust (also on GitHub Gist)

(function (dust) { /** * Polyfill to create String.trim() if it's not natively available */ if (!String.prototype.trim) { (function(){ // Make sure we trim BOM and NBSP var rtrim = /^[\\s\\uFEFF\\xA0]+|[\\s\\uFEFF\\xA0]+$/g; String.prototype.trim = function () { return this.replace(rtrim, ""); } })(); } /** * Processes the given string to escape special meta characters used within * Regular Expressions. This is used by the replace helper. */ function escapeRegExp(string) { return string.replace(/([.*+?^=!:$\{\}()|\\[\\]\\/\\\\])/g, "\\\\$1"); } /** * Performs a global search and replace within a string. * In the following example, we replace all periods in the * message string with dashes and we trim the result. * * {@replace str="{message}" search="." replace="-" trim="true" /} * * str - the input string within which the search and replace will be performed * search - the character or sequence to search * replace - the character or sequence used to replace * trim - when 'true', will trim the string before returning result. * */ dust.helpers.replace = function (chunk, ctx, bodies, params) { var str = dust.helpers.tap(params.str, chunk, ctx); var search = dust.helpers.tap(params.search, chunk, ctx); var replace = dust.helpers.tap(params.replace, chunk, ctx); var trim = dust.helpers.tap(params.trim, chunk, ctx); if(trim && trim == 'true') { str = str.trim(); } var result = str.replace(new RegExp(escapeRegExp(search), 'g'), replace); return chunk.write( result ); } })(typeof exports !== 'undefined' ? module.exports = require('dustjs-linkedin') : dust);