handlebars-helpers.js

/*! ******************************
  Handlebars helpers
  *******************************/

// debug helper
// usage: {{debug}} or {{debug someValue}}
// from: @commondream (http://thinkvitamin.com/code/handlebars-js-part-3-tips-and-tricks/)
Handlebars.registerHelper("debug", function(optionalValue) {
  console.log("Current Context");
  console.log("====================");
  console.log(this);
 
  if (optionalValue) {
    console.log("Value");
    console.log("====================");
    console.log(optionalValue);
  }
});


//  return the first item of a list only
// usage: {{#first items}}{{name}}{{/first}}
Handlebars.registerHelper('first', function(context, block) {
  return block(context[0]);
});

//Limit output
Handlebars.registerHelper('each_upto', function(ary, max, options) {
    if(!ary || ary.length == 0)
        return options.inverse(this);

    var result = [ ];
    for(var i = 0; i < max && i < ary.length; ++i)
        result.push(options.fn(ary[i]));
    return result.join('');
});

//<script id="tweets-template" type="text/x-handlebars-template" >
//    {{#each_upto this 5}}
//        <li>
//            <p>{{tweet}}</p>
//            <span id="author">{{author}}<span/>
//        </li>
//    {{/each_upto}}
//</script>


// a iterate over a specific portion of a list.
// usage: {{#slice items offset="1" limit="5"}}{{name}}{{/slice}} : items 1 thru 6
// usage: {{#slice items limit="10"}}{{name}}{{/slice}} : items 0 thru 9
// usage: {{#slice items offset="3"}}{{name}}{{/slice}} : items 3 thru context.length
// defaults are offset=0, limit=5
// todo: combine parameters into single string like python or ruby slice ("start:length" or "start,length")
Handlebars.registerHelper('slice', function(context, block) {
  var ret = "",
      offset = parseInt(block.hash.offset) || 0,
      limit = parseInt(block.hash.limit) || 5,
      i = (offset < context.length) ? offset : 0,
      j = ((limit + offset) < context.length) ? (limit + offset) : context.length;

  for(i,j; i<j; i++) {
    ret += block(context[i]);
  }

  return ret;
});




//  return a comma-serperated list from an iterable object
// usage: {{#toSentance tags}}{{name}}{{/toSentance}}
Handlebars.registerHelper('toSentance', function(context, block) {
  var ret = "";
  for(var i=0, j=context.length; i<j; i++) {
    ret = ret + block(context[i]);
    if (i<j-1) {
      ret = ret + ", ";
    };
  }
  return ret;
});



//  format an ISO date using Moment.js
//  http://momentjs.com/
//  moment syntax example: moment(Date("2011-07-18T15:50:52")).format("MMMM YYYY")
//  usage: {{dateFormat creation_date format="MMMM YYYY"}}
Handlebars.registerHelper('dateFormat', function(context, block) {
  if (window.moment) {
    var f = block.hash.format || "MMM Do, YYYY";
    return moment(Date(context)).format(f);
  }else{
    return context;   //  moment plugin not available. return data as is.
  };
});



<h3>{{trimString shortDesc}}</h3>
Handlebars.registerHelper('trimString', function(passedString) {
	
    var theString = passedString.substring(0,150);
    return new Handlebars.SafeString(theString);
});

<p>{{truncate description chars="150" append="..." }}</p>

Handlebars.registerHelper('truncate', function (context, options) {
 
    var chars = options.hash.chars || 20;
    var result = context;
 
    if (context.length > chars) {
    	
        result = result.substring(0, chars);
 
        if (options.hash.append) {
            result += options.hash.append;
        }

    }
 
    return new Handlebars.SafeString(result);

});


	Handlebars.registerHelper("debug", function(optionalValue) {

			console.log("Current Context");
			console.log("====================");
			console.log(this);

			if (optionalValue) {
			console.log("Value");
			console.log("====================");
			console.log(optionalValue);
			}

		});
		
		
		Handlebars.registerHelper('floor', function(value) {

			value = parseFloat(value);
			return Math.floor(value);

		});