Helper Expression

typedef

`method [EXPRESSION...]`

Calls method with zero or many arguments where each argument is a space separated EXPRESSION.

{{method 1 key call() hashProp=hashValue}}

Parameters

EXPRESSION {Literal Expression|KeyLookup Expression|Hash Expression|Call Expression}:
An expression that will be passed as an argument to method.

All Hash Expressions will be collectively added to the helperOptions's hash object.

If an EXPRESSION reads an observable, a compute will be passed to method.

Use

A helpers expression calls a function looked up in the helpers scope followed by the scope. It looks like:

Template:
    <h1>{{pluralize type ages.length}}</h1>

Data:
    {
      pluralize: function(type, count){
        return "data-pluralize"
      },
      todos: new List([22,32,42]),
      type: "age"
    }

Helpers:
    {
      pluralize: function(type, count){
        return type+(count() === 1 ? "" : "s")
      }
    }

Result:
    <h1>Ages</h1>

Helper expression arguments that are observable are passed a compute. This is in contrast to Call expressions that get passed the value.

Helper expression arguments are space seperated. If a Hash expression is an argument, the hash properties and values will be added to the helper options object. For example:

Template:
    <h1>{{pluralize word=type count=ages.length}}</h1>

Data:
    {
      todos: new List([22,32,42]),
      type: "age"
    }

Helpers:
    {
      pluralize: function(helperOptions){
        return helperOptions.hash.type+(helperOptions.hash.count() === 1 ? "" : "s")
      }
    }

Result:
    <h1>Ages</h1>