$idx and $len in a dust.js conditional statement

问题

The documentation on dust is just awful, I've already perused everything I can possibly find and cannot figure out how this is supposed to work.

I'm having this problem with the supposed special values $idx and $len, which, if I have guessed correctly, return the current index while iterating over an array-like section and the length of said array-like section. I have an @if condition (multiple actually) that I'm trying to workout to format a template, and the values are just not working as near as I can tell, which brings me to the following questions:

Are $idx and $len actual specials in dust.js?
Can you use them in an @if, and if so, how?
Assuming 1=true, is $idx zero-based?

Here is my template:

{#myArray}
  {name}{@sep}, {/sep}{@if cond="('{$idx}' == '{$len} - 2')"}and {/if}{@if cond="('{$idx}' == '{$len} - 1')"}{@if cond="('{$len}' == '1')"} is {:else} are {/if}here.{/if}
{/myArray}

What it's supposed to do:

If there is one person, render the string "Jake is here."
If there are two people, render the string "Jake and John are here."
If there are three or more people, render the string "Jake, John, and Bill are here." (obviously, adding the comma-separated names as necessary)

If the $idx and $len specials work the way one would think they work, this template would do what I want it to, as near as I can tell, however, I don't think either of $idx or $len (or both) are implemented. If they are not, how do I create a template that does what I want?

回答1:

Yes, they are special helpers in Dust.
But according to the dustjs-linkedin wiki (under the @if section), they cannot be used inside lists of primitives. In such cases you must use the following syntax:
```
{@idx}{.}{/idx}
```

Same applies with length. So, you're template would something like the template in this jsFiddle.

3.Yes, $idx and @idx are zero based. (See here for more info).

回答2:

But according to the dustjs-linkedin wiki (under the @if section), they cannot be used inside lists of primitives. In such cases you must use the following syntax:

{@idx}{.}{/idx}

this has changed now, and even in primitives the $idx and $len works

来源：https://stackoverflow.com/questions/11910070/idx-and-len-in-a-dust-js-conditional-statement

标签

dust.js