lb.base.template

Apply filters successively to input made of preceding arguments.

This method may be applied to several types of input, e.g. strings or DOM nodes, using different sets of filters according to expected types.

Design of HTML Templates

Here is a proposed solution for HTML Templates using this method.  The input would be a DOM node and a data object with named properties providing values for the replacement of parameters in attributes and text nodes.

var node = element('span',{},'Welcome #name#');
applyFilters(
  node,
  {
    name:'John Doe'
  },
  filters
);

The first filter may implement top-down parsing in the following way:

var ELEMENT_NODE = 1;
function topDownParsing(node,data,filters){
  if (!node || node.nodeType!==ELEMENT_NODE){
    return;
  }
  var i, length, attribute, child;
  for (i=0, length=node.attributes.length; i<length; i++){
    attribute = node.attributes[i];
    applyFilters(attribute,data,filters);
  }
  for (i=0, length=node.childNodes.length; i<length; i++){
    child = node.childNodes[i];
    applyFilters(child,data,filters);
  }
}

A more specific filter may replace parameters with corresponding values:

var PARAM_REGEXP = /#([a-zA-Z0-9\-]+)#/g;
function replaceParams(node,data){
  if ( !node || !node.nodeValue || !node.nodeValue.replace || !data ){
    return;
  }
  node.nodeValue = node.nodeValue.replace(
    PARAM_REGEXP,
    function(match,param){
      return data[param];
    }
  );
}

Design of String Templates

This is an alternate template system, using as input a string and an optional object for values of parameters to replace in the string.

var greeting = applyFilters(
                 'Welcome #name#',
                 {name: 'John Doe'},
                 filters
               );

A single filter may be provided here to operate the replacement, rewriting replaceParams from the previous example to adapt it to the new input types:

function replaceParamsInString(string, data){
  return string.replace(PARAM_REGEXP, function(match,param){
    return data[param];
  });
}

Parameters

• true or any truthy value to stop the processing
• undefined or any falsy value to continue with next filter

Returns

• the first value different from undefined returned by a filter; the following filters are not run
• undefined after running all filters, when all returned undefined

Note

Filters are applied from last (most specific) to first (least specific).  Unless processing is interrupted by a filter returning a value different from undefined, all filters will be applied in turn, in this order.