--- title: .Scratch description: Acts as a "scratchpad" to allow for writable page- or shortcode-scoped variables. godocref: date: 2017-02-01 publishdate: 2017-02-01 lastmod: 2017-02-01 keywords: [iteration] categories: [functions] menu: docs: parent: "functions" toc: signature: [] workson: [] hugoversion: relatedfuncs: [] deprecated: false draft: false aliases: [/extras/scratch/,/doc/scratch/] --- In most cases you can do okay without `Scratch`, but due to scoping issues, there are many use cases that aren't solvable in Go Templates without `Scratch`'s help. `.Scratch` is available as methods on `Page` and `Shortcode`. Since Hugo 0.43 you can also create a locally scoped `Scratch` using the template func `newScratch`. {{% note %}} See [this Go issue](https://github.com/golang/go/issues/10608) for the main motivation behind Scratch. {{% /note %}} {{% note %}} For a detailed analysis of `.Scratch` and in context use cases, see this [post](https://regisphilibert.com/blog/2017/04/hugo-scratch-explained-variable/). {{% /note %}} ## Get a Scratch From Hugo `0.43` you can also create a locally scoped `Scratch` by calling `newScratch`: ```go-html-template $scratch := newScratch $scratch.Set "greeting" "Hello" ``` A `Scratch` is also added to both `Page` and `Shortcode`. `Scratch` has the following methods: #### .Set Set the given value to a given key ```go-html-template {{ .Scratch.Set "greeting" "Hello" }} ``` #### .Get Get the value of a given key ```go-html-template {{ .Scratch.Set "greeting" "Hello" }} ---- {{ .Scratch.Get "greeting" }} > Hello ``` #### .Add Will add a given value to existing value of the given key. For single values, `Add` accepts values that support Go's `+` operator. If the first `Add` for a key is an array or slice, the following adds will be appended to that list. ```go-html-template {{ .Scratch.Add "greetings" "Hello" }} {{ .Scratch.Add "greetings" "Welcome" }} ---- {{ .Scratch.Get "greetings" }} > HelloWelcome ``` ```go-html-template {{ .Scratch.Add "total" 3 }} {{ .Scratch.Add "total" 7 }} ---- {{ .Scratch.Get "total" }} > 10 ``` ```go-html-template {{ .Scratch.Add "greetings" (slice "Hello") }} {{ .Scratch.Add "greetings" (slice "Welcome" "Cheers") }} ---- {{ .Scratch.Get "greetings" }} > []interface {}{"Hello", "Welcome", "Cheers"} ``` #### .SetInMap Takes a `key`, `mapKey` and `value` and add a map of `mapKey` and `value` to the given `key`. ```go-html-template {{ .Scratch.SetInMap "greetings" "english" "Hello" }} {{ .Scratch.SetInMap "greetings" "french" "Bonjour" }} ---- {{ .Scratch.Get "greetings" }} > map[french:Bonjour english:Hello] ``` #### .GetSortedMapValues Returns array of values from `key` sorted by `mapKey` ```go-html-template {{ .Scratch.SetInMap "greetings" "english" "Hello" }} {{ .Scratch.SetInMap "greetings" "french" "Bonjour" }} ---- {{ .Scratch.GetSortedMapValues "greetings" }} > [Hello Bonjour] ``` #### .Delete Removes the given key ```go-html-template {{ .Scratch.Delete "greetings" }} ``` ## Scope The scope of the backing data is global for the given `Page` or `Shortcode`, and spans partial and shortcode includes. Note that `.Scratch` from a shortcode will return the shortcode's `Scratch`, which in most cases is what you want. If you want to store it in the page scoped Scratch, then use `.Page.Scratch`. [pagevars]: /variables/page/