JavaScript Snippets: Programmable Text Expansion

Sometimes a template isn’t enough. You need to calculate a value, transform some text, or generate something programmatically. TypeSnap lets you write JavaScript directly in your snippets.

There are two ways to use JavaScript: the JavaScript content type (the entire snippet is a script) and the {{js:...}} macro (inline JavaScript within a regular snippet).

The JavaScript Content Type

When you set a snippet’s content type to JavaScript, the entire content is executed as a script. The return value becomes the expanded text.

1. Create a new snippet
2. Change the Type picker from Plain Text to JavaScript
3. Write your script. The last expression’s value (or an explicit return) is the output.

Example: Random Password

Abbreviation: ;pass Type: JavaScript

const chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefghjkmnpqrstwxyz23456789!@#$%';
let password = '';
for (let i = 0; i < 16; i++) {
  password += chars[Math.floor(Math.random() * chars.length)];
}
password;

Type ;pass and you get a random 16-character password. A new one every time.

Example: Unix Timestamp

Abbreviation: ;unix Type: JavaScript

Math.floor(Date.now() / 1000).toString();

Example: JSON Formatter

Abbreviation: ;jsonpretty Type: JavaScript

const raw = getClipboard();
try {
  JSON.stringify(JSON.parse(raw), null, 2);
} catch (e) {
  'Invalid JSON on clipboard';
}

Copy some minified JSON, type ;jsonpretty, and get the formatted version. The getClipboard() function reads the current clipboard contents.

The Inline Script Macro

For snippets where you need one computed value inside a larger template, use the {{js:...}} or {{javascript:...}} macro:

Today is day {{js:Math.ceil((new Date() - new Date(new Date().getFullYear(),0,1)) / 86400000)}} of the year.

The script runs inline, and its result replaces the macro.

Example: Week Number

Abbreviation: ;week

Week {{js:Math.ceil((((new Date() - new Date(new Date().getFullYear(),0,1)) / 86400000) + new Date(new Date().getFullYear(),0,1).getDay() + 1) / 7)}} of {{date:yyyy}}

Example: Countdown

Abbreviation: ;xmas

{{js:Math.ceil((new Date(new Date().getFullYear(), 11, 25) - new Date()) / 86400000)}} days until Christmas

Available Built-in Functions

TypeSnap’s JavaScript sandbox includes helper functions:

The sandbox also exposes date/time variables you can use directly: now (a Date object), year, month, day, hour, minute, second, and weekday.

Example: Title Case from Clipboard

Abbreviation: ;titlecase Type: JavaScript

capitalize(getClipboard());

Copy “the quick brown fox”, type ;titlecase, get “The Quick Brown Fox”.

Example: Word Count

Abbreviation: ;wc Type: JavaScript

const text = getClipboard();
const words = text.trim().split(/\s+/).length;
const chars = text.length;
words + ' words, ' + chars + ' characters';

Example: Slug Generator

Abbreviation: ;slug Type: JavaScript

lowercase(getClipboard())
  .replace(/[^a-z0-9\s-]/g, '')
  .replace(/\s+/g, '-')
  .replace(/-+/g, '-')
  .replace(/^-|-$/g, '');

Copy “My Blog Post Title!”, type ;slug, get my-blog-post-title.

Combining JavaScript with Fill-Ins

JavaScript snippets can coexist with fill-in macros. The fill-in dialog appears first; then the script runs with the filled-in values available.

Abbreviation: ;calc

{{input:Expression}} = {{js:eval('{{input:Expression}}')}}

Type ;calc, enter 24 * 365 in the dialog, get 24 * 365 = 8760.

Security

TypeSnap runs JavaScript in a sandboxed environment. Scripts:

• Cannot access the filesystem
• Cannot make network requests
• Cannot access other applications
• Cannot run shell commands
• Have limited environment variable access

The sandbox keeps your system safe even if you import snippets from an external source.

When to Use JavaScript vs. Macros

Use macros ({{date}}, {{random}}, etc.) when a built-in macro covers your need. They’re simpler, faster, and easier to read.

Use JavaScript when you need:

• String transformation (case conversion, formatting, encoding)
• Math calculations
• Conditional logic
• Processing clipboard content
• Generating structured data
• Anything a macro can’t do

JavaScript snippets are the escape hatch. When the built-in macros aren’t enough, you have a full programming language available.