Inline Templates Need Encoding.js

// This code is not safe

function renderTemplate(user) {
  return '<div>'
       + '  <div>' + user.name + '</div>'
       + '  <div>' + user.tel + '</div>'
       + '</div>';
}

// Why not?
// Well, if user.tel is not sanitized, the user could inject unwanted HTML, for example:
// renderTemplate({name: "Bobby", tel: "<font size='+5' color='red'><a href="//mypillz.com">BUY VIAGRA HERE</a></font>"});

// The solution is to encode the text before we insert it into the HTML.
// Here is the safe version.

function encodeForHTML(text) {
  return document.createElement('div')
           .appendChild(document.createTextNode(text))
           .parentNode.innerHTML;
}

function renderTemplate(user) {
  var safe = encodeForHTML;
  return '<div>'
       + '  <div>' + safe(user.name) + '</div>'
       + '  <div>' + safe(user.tel) + '</div>'
       + '</div>';
}

Alternative encoder implementations

Discussion on encoder methods

• But what if I want to do return '<div data-item="' + encodeAttribute(JSON.stringify(itemData)) + '">Item</div>'; ?

I don't have a function to encode attributes yet...

But anyway this approach of creating elements with jQuery and then turning them back to HTML again is not very efficient.

It could be more efficient to create all the elements in jQuery, and then let renderTemplate() return an HTMLElement (or jQuery wrapped element), instead of returning a String.