loop

Input:

{
  "list": [
    1,
    2,
    3
  ]
}

Template:

<template>
{
  "numbers": [
    {{loop list}}
      {{ . }}
    {{end}}
  ]
}
</template>

Output:

{
  "numbers": [
    1,
    2,
    3
  ]
}

The loop command iterates over arrays. The expression given must therefore return an array for the loop body to be executed. The loop body is invoked once for each element in the array. For each invocation, the context . will be set to the current element of the array.

In the above example, we did not explicitly place a comma in the loop body. However, JSON requires a comma to separate array values or pairs in objects. Therefore, the loop command automatically produces commas to separate its child productions.

You may also use a literal comma at the end of the loop body. This will not result in duplicate commas. However, as a literal comma is produced as part of each iteration, the last production will end with that comma. This may result in invalid JSON if the surrounding array or object ends after the loop.

Example: loop over non-JSON data

If the data to be used in a loop is not a JSON array, the array() function can be used to convert the data:

Input:

<html>
<body>
<ul id="list" foo="bar">
  <li>One</li>
  <li>Two</li>
  <li>Three</li>
</ul>
</body>
</html>

Template:

<template>
[
  {{loop array(/html/body/ul/li)}}
    {{.}}
  {{end}}
]
</template>

Output:

[
  "One",
  "Two",
  "Three"
]

Attributes passed to the array() function will be converted to elements with the attribute's name in its name attribute, and the value of the attribute as its content. This can be used to iterate over lists of attributes:

Template (identical input as above):

<template>
{
  {{loop array(//ul/@*)}}
    {{ @name }}: {{.}}
  {{end}}
}
</template>

Output:

{
  "id": "list",
  "foo": "bar"
}

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Last updated 4 years ago