具有自定义帮助程序的handlebars.js模板可切片数据数组

Question

im trying to set up a handlebars template using a custom helper but i can't seem to get it to work. The block helper should be able to slice my data array like it says here .

When i call every index in my array without using the helper my template it works properly.

This is my template

          <script id="template_marcas" type="text/x-handlebars-template">
          {{#datos_marcas}}
            <div class="large-3 small-3 columns marca_item">
              <div class="marca_content">
                <h3>{{img}}</h3>
                <p>{{descp}}</p>
                <a href="{{href}}">Ver descuentos</a>
              </div>
            </div>
          {{/datos_marcas}}
          </script>

My data array:

var data_marcas = { 
  datos_marcas: [
      {
        "img":"alverto",
        "descp":"Descripción Marta",
        "href":"test"
      },
       {
        "img":"marta",
        "descp":"Descripción Marca",
        "href":"test"
      },
       {
        "img":"marca",
        "descp":"Descripción Marca",
        "href":"test"
      } //etc.....
    ]
  };

And this is the helper i'm trying to use

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;
});

which i found here

EDIT

I'm trying to use the helper as below, perhaps there is something wrong with the way i'm calling it.

          <script id="template_marcas" type="text/x-handlebars-template">
          {{#slice datos_marcas offset="1" limit="5"}}
            <div class="large-3 small-3 columns marca_item">
              <div class="marca_content">
                <h3>{{img}}</h3>
                <p>{{descp}}</p>
                <a href="{{href}}">Ver descuentos</a>
              </div>
            </div>
          {{/slice}}
          </script>

Answer 1

There is error in the slice helper you found.

Instead of block(context[i]) there should be block.fn(context[i])

Here is a working jsfiddle

Answer 2

I upgraded this so you can use negative offset to strip from the end of the array as per ECMA Array.slice.

Handlebars.registerHelper('slice', function (context, options) {

  var ret = "",
    offset = parseInt(options.hash.offset, 10) || 0,
    limit = parseInt(options.hash.limit, 10) || 5,
    i,
    j;

  if (offset < 0) {
    i = (-offset < context.length) ? context.length - (-offset) : 0;
  } else {
    i = (offset < context.length) ? offset : 0;
  }

  j = ((limit + i) < context.length) ? (limit + i) : context.length;

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

  return ret;
});

See the fiddle.