Creating your own snippets in vs code

程序员文章站 2024-03-23 20:14:22

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Snippets show in IntelliSense (Ctrl+Space) mixed with other suggestions as well as in a dedicated snippet picker (Insert Snippet in the Command Palette). There is also support for tab-completion: Enable it with "editor.tabCompletion": true, type a snippet prefix, and press Tab to insert a snippet.

The snippet syntax follows the TextMate snippet syntax with the exception of 'interpolated shell code', which is not supported.

Creating your own snippets

You can define your own snippets, either global snippets or snippets for a specific language. To open up a snippet file for editing, select User Snippets under File > Preferences (Code > Preferences on macOS) and select the language (by language identifier) for which the snippets should appear or create a new global snippet (New Global Snippets file...).

Creating your own snippets in vs code

Snippets are defined in a JSON format. The example below is a For Loop snippet you would use for JavaScript:

{
    "For_Loop": {
        "prefix": "for",
        "body": [
          "for (const ${2:element} of ${1:array}) {",
          "\t$0",
          "}"
        ],
        "description": "For Loop"
    },
}

In the example above:

For Loop is the snippet name.
prefix defines how this snippet is selected from IntelliSense and tab completion. In this case for.
body is the content and either a single string or an array of strings of which each element will be inserted as separate line.
description is the description used in the IntelliSense drop down.

The example above has two placeholders, ${1:array} and ${2:element}. You can quickly traverse them in the order of their number. The string after the number and colon is used as an initial default.

Snippet filenames

The file type and name define if a snippet is global or specific to a language. Snippets stored in a JSON file that is named after a language identifier (<languageId>.json) are language specific. For example, JavaScript-only snippets go in a javascript.json file.

Global snippets

Global snippets that are applicable whenever you are editing and are stored in <name>.code-snippets files, for example MyGlobal.code-snippets. The JSON schema of global snippets allows you to define a scope property which can filter the languages (based on language identifier) for which a snippet is applicable.

The sample below is the For Loop again but this time it is scoped to JavaScript andTypeScript.

{
    "For_Loop": {
        "prefix": "for",
        "scope": "javascript,typescript",
        "body": [
          "for (const ${2:element} of ${1:array}) {",
          "\t$0",
          "}"
        ],
        "description": "For Loop"
    },
}

Once you have added a new snippet, you can try it out right away, no restart needed.

Snippet syntax

The body of a snippet can use special constructs to control cursors and the text being inserted. The following are supported features and their syntaxes:

Tabstops

With tabstops, you can make the editor cursor move inside a snippet. Use $1, $2 to specify cursor locations. The number is the order in which tabstops will be visited, whereas $0 denotes the final cursor position. Multiple occurrences of the same tabstop are linked and updated in sync.

Placeholders

Placeholders are tabstops with values, like ${1:foo}. The placeholder text will be inserted and selected such that it can be easily changed. Placeholders can be nested, like ${1:another ${2:placeholder}}.

Choice

Placeholders can have choices as values. The syntax is a comma separated enumeration of values, enclosed with the pipe-character, for example ${1|one,two,three|}. When the snippet is inserted and the placeholder selected, choices will prompt the user to pick one of the values.

Variables

With $name or ${name:default} you can insert the value of a variable. When a variable isn’t set, its default or the empty string is inserted. When a variable is unknown (that is, its name isn’t defined) the name of the variable is inserted and it is transformed into a placeholder.

The following variables can be used:

TM_SELECTED_TEXT The currently selected text or the empty string
TM_CURRENT_LINE The contents of the current line
TM_CURRENT_WORD The contents of the word under cursor or the empty string
TM_LINE_INDEX The zero-index based line number
TM_LINE_NUMBER The one-index based line number
TM_FILENAME The filename of the current document
TM_FILENAME_BASE The filename of the current document without its extensions
TM_DIRECTORY The directory of the current document
TM_FILEPATH The full file path of the current document
CLIPBOARD The contents of your clipboard

For inserting the current date and time:

CURRENT_YEAR The current year
CURRENT_YEAR_SHORT The current year's last two digits
CURRENT_MONTH The month as two digits (example '02')
CURRENT_MONTH_NAME The full name of the month (example 'July')
CURRENT_MONTH_NAME_SHORT The short name of the month (example 'Jul')
CURRENT_DATE The day of the month
CURRENT_DAY_NAME The name of day (example 'Monday')
CURRENT_DAY_NAME_SHORT The short name of the day (example 'Mon')
CURRENT_HOUR The current hour in 24-hour clock format
CURRENT_MINUTE The current minute
CURRENT_SECOND The current second

Variable transforms

Transformations allow you to modify the value of a variable before it is inserted. The definition of a transformation consists of three parts:

A regular expression that is matched against the value of a variable, or the empty string when the variable cannot be resolved.
A "format string" that allows to reference matching groups from the regular expression. The format string allows for conditional inserts and simple modifications.
Options that are passed to the regular expression.

The following example inserts the name of the current file without its ending, so from foo.txt it makes foo.

${TM_FILENAME/(.*)\\..+$/$1/}
  |           |         | |
  |           |         | |-> no options
  |           |         |
  |           |         |-> references the contents of the first
  |           |             capture group
  |           |
  |           |-> regex to capture everything before
  |               the final `.suffix`
  |
  |-> resolves to the filename

Grammar

Below is the EBNF (extended Backus-Naur form) for snippets. With \ (backslash), you can escape $, } and \. Within choice elements, the backslash also escapes comma and pipe characters.

any         ::= tabstop | placeholder | choice | variable | text
tabstop     ::= '$' int | '${' int '}'
placeholder ::= '${' int ':' any '}'
choice      ::= '${' int '|' text (',' text)* '|}'
variable    ::= '$' var | '${' var }'
                | '${' var ':' any '}'
                | '${' var '/' regex '/' (format | text)+ '/' options '}'
format      ::= '$' int | '${' int '}'
                | '${' int ':' '/upcase' | '/downcase' | '/capitalize' '}'
                | '${' int ':+' if '}'
                | '${' int ':?' if ':' else '}'
                | '${' int ':-' else '}' | '${' int ':' else '}'
regex       ::= JavaScript Regular Expression value (ctor-string)
options     ::= JavaScript Regular Expression option (ctor-options)
var         ::= [_a-zA-Z] [_a-zA-Z0-9]*
int         ::= [0-9]+
text        ::= .*

Using TextMate snippets

You can also use existing TextMate snippets (.tmSnippets) with VS Code. See the Using TextMate Snippets topic in our Extension Authoring section to learn more.

Assign keybindings to snippets

You can create custom keybindings to insert specific snippets. Open keybindings.json (Preferences: Open Keyboard Shortcuts File), which defines all your keybindings, and add a keybinding passing "snippet" as an extra argument:

{
  "key": "cmd+k 1",
  "command": "editor.action.insertSnippet",
  "when": "editorTextFocus",
  "args": {
    "snippet": "console.log($1)$0"
  }
}

The keybinding will invoke the Insert Snippet command but instead of prompting you to select a snippet, it will insert the provided snippet. You define the custom keybinding as usual with a keyboard shortcut, command id, and optional when clause context for when the keyboard shortcut is enabled.

Also, instead of using the snippet argument value to define your snippet inline, you can reference an existing snippet by using the langId and name arguments :

{
  "key": "cmd+k 1",
  "command": "editor.action.insertSnippet",
  "when": "editorTextFocus",
  "args": {
    "langId": "csharp",
    "name": "myFavSnippet"
  }
}

Next Steps

Command Line - VS Code has a rich command line interface to open or diff files and install extensions.
Extending Visual Studio Code - Learn about other ways to extend VS Code.
Themes, Snippets, and Colorizers - You can package themes, snippets and language colorizers for use in VS Code.

Common Questions

Q: What if I want to use existing TextMate snippets from a .tmSnippet file?

A: You can easily package TextMate snippets files for use in VS Code. See Using TextMate Snippets in our Extension Authoring documentation.

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Creating your own snippets in vs code

Creating your own snippets

Snippet filenames

Global snippets

Snippet syntax

Tabstops

Placeholders

Choice

Variables

Variable transforms

Grammar

Using TextMate snippets

Assign keybindings to snippets

Next Steps

Common Questions

Creating your own snippets in vs code

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