The b:eval tag, or the evaluate tag, is a tag for evaluating the value of an expression. It differs from the data tag in that data tags emit a single value, whereas b:eval tags can combine or modify data values using an expression.


expr - Expression to evaluate. 

Example usage

Resize an image with an operator call

The following example emits the post title and body for each of the posts in the data:posts dictionary.
  .post-thumbnail {
    background-image: url(
        <b:eval expr='resizeImage(data:post.featuredImage, 385).cssEscaped' />);