vscode-postfix-ts

Postfix templates for TypeScript/JavaScript

Features

This extension features postfix templates that can be used to improve productivity. It's been inspired on former, great R# extension

I find it annoying to jump the cursor back and forth whenever I want to perform some simple operations. This extension makes it easier. I use this feature on daily basis in C# but was missing it in JS/TS until now.

A simple animation is worth more than words:

It also works pretty well with multiline expressions (v1.9.0+):

There is also a special handling for .not template which allows you to select specific expression to invert when having more options:

All available templates (expr means the expression on which the template is applied):

Template	Outcome
.if	if (expr)
.else	if (!expr)
.null	if (expr === null)
.notnull	if (expr !== null)
.undefined	if (expr === undefined) or if (typeof expr === "undefined") (see settings)
.notundefined	if (expr !== undefined) or if (typeof expr !== "undefined") (see settings)
.for	for (let i = 0; i < expr.Length; i++)
.forof	for (const item of expr)
.forin	for (const item in expr)
.foreach	expr.forEach(item => )
.not	!expr
.return	return expr
.var	var name = expr
.let	let name = expr
.const	const name = expr
.log	console.log(expr)
.error	console.error(expr)
.warn	console.warn(expr)
.cast	(<SomeType>expr)
.castas	(expr as SomeType)
.call	{cursor}(expr)
.new	new expr()
.promisify	Promise<expr>
.await	await expr

If for any reason you don't like either of those templates you can disable them one by one using postfix.disabledBuiltinTemplates setting.

Custom templates (1.6.0 and above)

You can now add your own templates if the defaults are not enough. This will only work for simple ones as some templates require additional tricky handling. To configure a template you need to set postfix.customTemplates setting. It's an array of the following objects:

{
  "name": "...",
  "description": "...",
  "body": "...",
  "when": ["..."]
}

name defines what will be the name of the suggestion description will show additional optional description when suggestion panel is opened body defines how the template will work (see below) when defines conditions when the template should be suggested

Template body

Template body defines how will the expression before the cursor be replaced. Body can be defined either as single string or array of strings. If it's an array then strings will be joined with a newline character. It supports standard Visual Studio Code Snippet syntax. There is also one special placeholder that can be used:

• {{expr}}: this will be replaced by the expression on which the template is applied so for example !{{expr}} will simply negate the expression
• this placeholder can have modifiers (upper, lower, capitalize) which can be used in the following way:

{
    "name": "useState",
    "body": "const [{{expr}}, set{{expr:capitalize}}] = React.useState();",
    "description": "const [{{expr}}, set{{expr:capitalize}}] = React.useState();",
    "when": []
}

This snippet will have the following outcome (name of the original identifier has been capitalized):

Template conditions

when condition can be zero or more of the following options:

• identifier: simple identifier, ie. variableName (inside an if statement or function call arguments)
• expression: can be either a simple expression like object.property.value or array[index] or a combination of them
• binary-expression: a binary expression, ie. x > 3, x * 100, x && y
• unary-expression: an unary expression, ie. !x, x++ or ++x
• new-expression: a new expression, ie. new Type(arg1, arg2)
• function-call: a function call expression, ie. func(), object.method() and so on
• type: type in function/variable definition, ie. const x: string
• string-literal: string literal, ie. 'a string' or "string in double quotes"

If no conditions are specified then given template will be available under all possible situations

Infer variable names (1.11.0 and above)

For var/let/const and forof/foreach templates the extension will try to infer a better name for the variable based on the subject expression. For instance fs.readFile() expression will result in variable named file instead of default name. Same applies to forof/foreach templates, but in this case the extension is trying to figure out a singular form of the subject. Of course this can still be easily changed, it's only a suggestion. Few examples on the image below:

If you have ideas for more "patterns" that could be easily handled please create an issue.

Configuration

This plugin contributes the following settings:

• postfix.languages: array of language identifiers in which the extension will be available. Default value is ['javascript', 'typescript', 'javascriptreact', 'typescriptreact']
• postfix.customTemplates: array of custom template definitions - see Custom templates (1.6.0 and above)
• postfix.customTemplates.mergeMode: determines how custom templates are shown if they share the same name with built-in template:
  • append - both built-in and custom template will be shown
  • override - only custom template will be shown (it overrides built-in one)
• postfix.undefinedMode: determines the behavior of .undefined and .notundefined templates, either equality comparison or typeof
• postfix.inferVariableName: enables variable name inferring
• postfix.disabledBuiltinTemplates: allows to disable particular built-in templates (for instance discouraged var)

The postfix.languages setting can be used to make the extension available for inline JS/TS which is in other files like .html, .vue or others. You must still include javascript and typescript if you want the extension to be available there among the others.

Known issues

Feel free to open issues for whatever you think may improve the extension's value. New ideas for more templates are also welcome. Most of them are pretty easy to implement.