ref: c9403cbceaaeff53ff4833561f4eefe1dc1a405e
dir: /content/en/functions/safeJS.md/
---
title: safeJS
# linktitle:
description: Declares the provided string as a known safe JavaScript string.
godocref: https://golang.org/src/html/template/content.go?s=2548:2557#L51
date: 2017-02-01
publishdate: 2017-02-01
lastmod: 2017-02-01
categories: [functions]
menu:
docs:
parent: "functions"
keywords: [strings]
signature: ["safeJS INPUT"]
workson: []
hugoversion:
relatedfuncs: []
deprecated: false
draft: false
aliases: []
---
In this context, *safe* means the string encapsulates a known safe EcmaScript5 Expression (e.g., `(x + y * z())`).
Template authors are responsible for ensuring that typed expressions do not break the intended precedence and that there is no statement/expression ambiguity as when passing an expression like `{ foo:bar() }\n['foo']()`, which is both a valid expression and a valid program with a very different meaning.
Example: Given `hash = "619c16f"` defined in the front matter of your `.md` file:
* <span class="good">`<script>var form_{{ .Params.hash | safeJS }};…</script>` → `<script>var form_619c16f;…</script>`</span>
* <span class="bad">`<script>var form_{{ .Params.hash }};…</script>` → `<script>var form_"619c16f";…</script>`</span>