string-kit

What is string-kit?

string-kit is a versatile JavaScript library for string manipulation. It provides a wide range of utilities for working with strings, including formatting, padding, alignment, and more.

What are string-kit's main functionalities?

String Formatting

The `format` function allows you to format strings using placeholders, similar to printf in C. This is useful for creating dynamic strings based on variable values.

const string = require('string-kit');
console.log(string.format('%s is %d years old.', 'Alice', 30));

String Padding

The `pad` function pads a string to a specified length with a given character. This is useful for aligning text in console output or creating fixed-width string representations.

const string = require('string-kit');
console.log(string.pad('Hello', 10, ' '));

String Alignment

The `align` function aligns a string within a specified width, either left, right, or center. This is useful for formatting text in tables or other structured formats.

const string = require('string-kit');
console.log(string.align('Hello', 10, 'center', ' '));

String Truncation

The `truncate` function shortens a string to a specified length, optionally adding an ellipsis or other suffix. This is useful for displaying previews or summaries of longer text.

const string = require('string-kit');
console.log(string.truncate('This is a long string', 10));

Other packages similar to string-kit

string

The `string` package provides a wide range of string manipulation utilities, including trimming, padding, and formatting. It is similar to string-kit but offers a different API and some additional features.

lodash

Lodash is a utility library that provides a wide range of functions for working with arrays, objects, and strings. It includes string manipulation functions like padding, truncation, and case conversion. While it is more general-purpose than string-kit, it offers similar string manipulation capabilities.

underscore.string

underscore.string is a string manipulation library that extends Underscore.js with additional string functions. It provides utilities for trimming, padding, formatting, and more. It is similar to string-kit but designed to work seamlessly with Underscore.js.

README

String Kit

A string manipulation toolbox, featuring a string formatter (inspired by sprintf), a variable inspector (output featuring ANSI colors and HTML) and various escape functions (shell argument, regexp, html, etc).

• License: MIT
• Current status: beta
• Platform: Node.js only (browser support is planned)

Install

Use Node Package Manager:

npm install string-kit

Reference

• .format()
• .format.count()
• .inspect()
• Escape functions collection
  • .escape.shellArg()
  • .escape.regExp()
  • .escape.regExpPattern()
  • .escape.regExpReplacement()
  • .escape.html()
  • .escape.htmlAttr()
  • .escape.htmlSpecialChars()
  • .escape.control()

.format( formatString , ... )

• formatString String a string containing some sprintf()-like formating
• ... mixed a variable list of arguments to insert into the formatString

This function is inspired by the C's sprintf() function.

Basicly, if formatString includes format specifiers (subsequences beginning with %), the additional arguments following formatString are formatted and inserted in the resulting string replacing their respective specifiers.

Also it diverges from C in quite a few places.

Basic usage:

var format = require( 'string-kit' ).format ;
console.log( format( 'Hello %s %s, how are you?' , 'Joe' , 'Doe' ) ) ;
// Output: 'Hello Joe Doe, how are you?'

Specifiers:

• %% write a single %
• %s string
• %f float
• %d or %i integer
• %u unsigned integer
• %U unsigned positive integer (>0)
• %h unsigned hexadecimal
• %x unsigned hexadecimal, force pair of symbols (e.g. 'f' -> '0f')
• %o unsigned octal
• %b unsigned binary
• %J JSON.stringify()
• %D drop, the argument does not produce anything but is eaten anyway
• %[ filter function existing in the this context, e.g. %[filter:%a%a]
• %a argument for a filter function

Few examples:

var format = require( 'string-kit' ).format ;

console.log( format( 'This company regains %d%% of market share.' , 36 ) ) ;
// Output: 'This company regains 36% of market share.'

console.log( format( '11/8=%f' , 11/8 ) ) ;
// Output: '11/8=1.375'

console.log( format( 'Hexa %h %x' , 11 , 11 ) ) ;
// Output: 'Hexa b 0b'

We can insert a number between the % sign and the letter of the specifier, this way, rather than using the next argument, it uses the Nth argument, this is the absolute position:

console.log( format( '%2s%1s%3s' , 'A' , 'B' , 'C' ) ) ; // 'BAC'

Also, the internal pointer is moved anyway, so the Nth format specifier still use the Nth argument if it doesn't specify any position:

console.log( format( '%2s%s%s' , 'A' , 'B' , 'C' ) ) ; // 'BBC'

If the number is preceded by a plus or a minus sign, the relative position is used rather than the absolute position.

console.log( format( '%+1s%-1s%s' , 'A' , 'B' , 'C' ) ) ; // 'BAC'

Use case: language.

var hello = {
	en: 'Hello %s %s!' ,
	jp: 'Konnichiwa %2s %1s!'
} ;

console.log( format( hello[ lang ] , firstName , lastName ) ) ;
// Output the appropriate greeting in a language.
// In japanese the last name will come before the first name,
// but the argument list doesn't need to be changed.

The mysterious %[ format specifier is used when we want custom formatter. Firstly we need to build an object containing one or many functions. Then, format() should be used with call(), to pass the functions collection as the this context.

The %[ is followed by the function's name, followed by a :, followed by a variable list of arguments using %a. It is still possible to use relative and absolute positionning. The whole format specifier is finished when a ] is encountered.

Example:

var filters = {
	fxy: function( a , b ) { return '' + ( a * a + b ) ; }
} ;

console.log( format.call( filters , '%s%[fxy:%a%a]' , 'f(x,y)=' , 5 , 3 ) ) ;
// Output: 'f(x,y)=28'

console.log( format.call( filters , '%s%[fxy:%+1a%-1a]' , 'f(x,y)=' , 5 , 3 ) ) ;
// Output: 'f(x,y)=14'

.format.count( formatString )

• formatString String a string containing some sprintf()-like formating

It just counts the number of format specifier in the formatString.

.inspect( [options] , variable )

• options Object display options, the following key are possible:
  • style String this is the style to use, the value can be:
    • 'none': (default) normal output suitable for console.log() or writing into a file
    • 'color': colorful output suitable for terminal
    • 'html': html output
  • depth: depth limit, default: 3
  • nofunc: do not display functions
  • funcDetails: display function's details
  • proto: display object's prototype
• variable mixed anything we want to inspect/debug

It inspect a variable, and return a string ready to be displayed with console.log(), or even as HTML output.

It produces a slightly better output than node's util.inspect(), with more options to control what should be displayed.

Since options come first, it is possible to use bind() to create some custom variable inspector.

For example:

var colorInspect = require( 'string-kit' ).inspect.bind( undefined , { style: 'color' } ) ;

Escape functions collection

.escape.shellArg( str )

• str String the string to filter

It escapes the string so that it will be suitable as a shell command's argument.

.escape.regExp( str ) , .escape.regExpPattern( str )

• str String the string to filter

It escapes the string so that it will be suitable to inject it in a regular expression's pattern as a literal string.

Example of a search and replace from a user's input:

var result = data.replace(
	new RegExp( stringKit.escape.regExp( userInputSearch ) , 'g' ) ,
	stringKit.escape.regExpReplacement( userInputReplace )
) ;

.escape.regExpReplacement( str )

• str String the string to filter

It escapes the string so that it will be suitable as a literal string for a regular expression's replacement.

.escape.html( str )

• str String the string to filter

It escapes the string so that it will be suitable as HTML content.

Only < > & are replaced by HTML entities.

.escape.htmlAttr( str )

• str String the string to filter

It escapes the string so that it will be suitable as an HTML tag attribute's value.

Only < > & " are replaced by HTML entities.

It assumes valid HTML: the attribute's value should be into double quote, not in single quote.

.escape.htmlSpecialChars( str )

• str String the string to filter

It escapes all HTML special characters, < > & " ' are replaced by HTML entities.

.escape.control( str )

• str String the string to filter

It escapes all ASCII control characters (code lesser than or equals to 0x1F, or backspace).

Carriage return, newline and tabulation are respectively replaced by \r, \n and \t. Other characters are replaced by the unicode notation, e.g. NUL is replaced by \x00.

Full BDD spec generated by Mocha:

TOC

• format()
• Escape collection
• inspect()

format()

should perform basic examples.

expect( format( 'Hello world' ) ).to.be( 'Hello world' ) ;
expect( format( 'Hello %s' , 'world' ) ).to.be( 'Hello world' ) ;
expect( format( 'Hello %s %s, how are you?' , 'Joe' , 'Doe' ) ).to.be( 'Hello Joe Doe, how are you?' ) ;
expect( format( 'I have %i cookies.' , 3 ) ).to.be( 'I have 3 cookies.' ) ;
expect( format( 'This company regains %d%% of market share.' , 36 ) ).to.be( 'This company regains 36% of market share.' ) ;
expect( format( '11/8=%f' , 11/8 ) ).to.be( '11/8=1.375' ) ;
expect( format( 'Binary %b %b' , 11 , 123 ) ).to.be( 'Binary 1011 1111011' ) ;
expect( format( 'Octal %o %o' , 11 , 123 ) ).to.be( 'Octal 13 173' ) ;
expect( format( 'Hexa %h %x %x' , 11 , 11 , 123 ) ).to.be( 'Hexa b 0b 7b' ) ;
expect( format( 'JSON %J' , {hello:'world',here:'is',my:{wonderful:'object'}} ) ).to.be( 'JSON {"hello":"world","here":"is","my":{"wonderful":"object"}}' ) ;

%u should format unsigned integer.

expect( format( '%u' , 123 ) ).to.be( '123' ) ;
expect( format( '%u' , 0 ) ).to.be( '0' ) ;
expect( format( '%u' , -123 ) ).to.be( '0' ) ;
expect( format( '%u' ) ).to.be( '0' ) ;

%U should format positive unsigned integer.

expect( format( '%U' , 123 ) ).to.be( '123' ) ;
expect( format( '%U' , 0 ) ).to.be( '1' ) ;
expect( format( '%U' , -123 ) ).to.be( '1' ) ;
expect( format( '%U' ) ).to.be( '1' ) ;

should perform well the argument's number feature.

expect( format( '%s%s%s' , 'A' , 'B' , 'C' ) ).to.be( 'ABC' ) ;
expect( format( '%+1s%-1s%s' , 'A' , 'B' , 'C' ) ).to.be( 'BAC' ) ;
expect( format( '%3s%s' , 'A' , 'B' , 'C' ) ).to.be( 'CBC' ) ;

format.count() should count the number of arguments found.

expect( format.count( 'blah blih blah' ) ).to.be( 0 ) ;
expect( format.count( 'blah blih %% blah' ) ).to.be( 0 ) ;
expect( format.count( '%i %s' ) ).to.be( 2 ) ;
expect( format.count( '%[unexistant]' ) ).to.be( 0 ) ;
expect( format.count( '%[unexistant:%a%a]' ) ).to.be( 2 ) ;

format.hasFormatting() should return true if the string has formatting and thus need to be interpreted, or false otherwise.

expect( format.hasFormatting( 'blah blih blah' ) ).to.be( false ) ;
expect( format.hasFormatting( 'blah blih %% blah' ) ).to.be( true ) ;
expect( format.hasFormatting( '%i %s' ) ).to.be( true ) ;
expect( format.hasFormatting( '%[unexistant]' ) ).to.be( true ) ;
expect( format.hasFormatting( '%[unexistant:%a%a]' ) ).to.be( true ) ;

when using a filter object as the this context, the %[functionName] format should use a custom function to format the input.

var filters = {
	fixed: function() { return 'F' ; } ,
	double: function( str ) { return '' + str + str ; } ,
	fxy: function( a , b ) { return '' + ( a * a + b ) ; }
} ;

expect( format.call( filters , '%[fixed]' ) ).to.be( 'F' ) ;
expect( format.call( filters , '%[fixed]%s%s%s' , 'A' , 'B' , 'C' ) ).to.be( 'FABC' ) ;
expect( format.call( filters , '%s%[fxy:%a%a]' , 'f(x,y)=' , 5 , 3 ) ).to.be( 'f(x,y)=28' ) ;
expect( format.call( filters , '%s%[fxy:%+1a%-1a]' , 'f(x,y)=' , 5 , 3 ) ).to.be( 'f(x,y)=14' ) ;
expect( format.call( filters , '%[unexistant]' ) ).to.be( '' ) ;

Escape collection

escape.control() should escape control characters.

expect( string.escape.control( 'Hello\n\t... world!' ) ).to.be( 'Hello\\n\\t... world!' ) ;
expect( string.escape.control( 'Hello\\n\\t... world!' ) ).to.be( 'Hello\\n\\t... world!' ) ;
expect( string.escape.control( 'Hello\\\n\\\t... world!' ) ).to.be( 'Hello\\\\n\\\\t... world!' ) ;
expect( string.escape.control( 'Hello\\\\n\\\\t... world!' ) ).to.be( 'Hello\\\\n\\\\t... world!' ) ;

expect( string.escape.control( 'Nasty\x00chars\x1bhere\x7f!' ) ).to.be( 'Nasty\\x00chars\\x1bhere\\x7f!' ) ;

escape.shellArg() should escape a string so that it will be suitable as a shell command's argument.

//console.log( 'Shell arg:' , string.escape.shellArg( "Here's my shell's argument" ) ) ;
expect( string.escape.shellArg( "Here's my shell's argument" ) ).to.be( "'Here'\\''s my shell'\\''s argument'" ) ;

escape.regExp() should escape a string so that it will be suitable as a literal string into a regular expression pattern.

//console.log( 'String in RegExp:' , string.escape.regExp( "(This) {is} [my] ^$tring^... +doesn't+ *it*? |yes| \\no\\ /maybe/" ) ) ;
expect( string.escape.regExp( "(This) {is} [my] ^$tring^... +doesn't+ *it*? |yes| \\no\\ /maybe/" ) )
	.to.be( "\\(This\\) \\{is\\} \\[my\\] \\^\\$tring\\^\\.\\.\\. \\+doesn't\\+ \\*it\\*\\? \\|yes\\| \\\\no\\\\ \\/maybe\\/" ) ;

escape.regExpReplacement() should escape a string so that it will be suitable as a literal string into a regular expression replacement.

expect( string.escape.regExpReplacement( "$he love$ dollar$ $$$" ) ).to.be( "$$he love$$ dollar$$ $$$$$$" ) ;

expect(
	'$he love$ dollar$ $$$'.replace(
		new RegExp( string.escape.regExp( '$' ) , 'g' ) ,
		string.escape.regExpReplacement( '$1' )
	) 
).to.be( "$1he love$1 dollar$1 $1$1$1" ) ;

escape.html() should escape a string so that it will be suitable as HTML content.

//console.log( string.escape.html( "<This> isn't \"R&D\"" ) ) ;
expect( string.escape.html( "<This> isn't \"R&D\"" ) ).to.be( "&lt;This&gt; isn't \"R&amp;D\"" ) ;

escape.htmlAttr() should escape a string so that it will be suitable as an HTML tag attribute's value.

//console.log( string.escape.htmlAttr( "<This> isn't \"R&D\"" ) ) ;
expect( string.escape.htmlAttr( "<This> isn't \"R&D\"" ) ).to.be( "&lt;This&gt; isn't &quot;R&amp;D&quot;" ) ;

escape.htmlSpecialChars() should escape all HTML special characters.

//console.log( string.escape.htmlSpecialChars( "<This> isn't \"R&D\"" ) ) ;
expect( string.escape.htmlSpecialChars( "<This> isn't \"R&D\"" ) ).to.be( "&lt;This&gt; isn&#039;t &quot;R&amp;D&quot;" ) ;

inspect()

should inspect a variable with default options accordingly.

var MyClass = function MyClass() {
	this.variable = 1 ;
} ;

MyClass.prototype.report = function report() { console.log( 'Variable value:' , this.variable ) ; } ;
MyClass.staticFunc = function staticFunc() { console.log( 'Static function.' ) ; } ;

var sparseArray = [] ;
sparseArray[ 3 ] = 'three' ;
sparseArray[ 10 ] = 'ten' ;
sparseArray[ 20 ] = 'twenty' ;
sparseArray.customProperty = 'customProperty' ;

var object = {
	a: 'A' ,
	b: 2 ,
	str: 'Woot\nWoot\rWoot\tWoot' ,
	sub: {
		u: undefined ,
		n: null ,
		t: true ,
		f: false
	} ,
	emptyString: '' ,
	emptyObject: {} ,
	list: [ 'one','two','three' ] ,
	emptyList: [] ,
	sparseArray: sparseArray ,
	hello: function hello() { console.log( 'Hello!' ) ; } ,
	anonymous: function() { console.log( 'anonymous...' ) ; } ,
	class: MyClass ,
	instance: new MyClass() ,
	buf: new Buffer( 'This is a buffer!' )
} ;

object.sub.circular = object ;

Object.defineProperties( object , {
	c: { value: '3' } ,
	d: {
		get: function() { throw new Error( 'Should not be called by the test' ) ; } ,
		set: function( value ) {}
	}
} ) ;

//console.log( '>>>>>' , string.escape.control( string.inspect( object ) ) ) ;
//console.log( string.inspect( { style: 'color' } , object ) ) ;
expect( string.inspect( object ) ).to.be( '<Object> <object> {\n    a: "A" <string>(1)\n    b: 2 <number>\n    str: "Woot\\nWoot\\rWoot\\tWoot" <string>(19)\n    sub: <Object> <object> {\n        u: undefined\n        n: null\n        t: true\n        f: false\n        circular: <Object> <object> [circular]\n    }\n    emptyString: "" <string>(0)\n    emptyObject: <Object> <object> {}\n    list: <Array>(3) <object> {\n        [0] "one" <string>(3)\n        [1] "two" <string>(3)\n        [2] "three" <string>(5)\n        length: 3 <number> <-conf -enum>\n    }\n    emptyList: <Array>(0) <object> {\n        length: 0 <number> <-conf -enum>\n    }\n    sparseArray: <Array>(21) <object> {\n        [3] "three" <string>(5)\n        [10] "ten" <string>(3)\n        [20] "twenty" <string>(6)\n        length: 21 <number> <-conf -enum>\n        customProperty: "customProperty" <string>(14)\n    }\n    hello: <Function> hello(0) <function>\n    anonymous: <Function> (anonymous)(0) <function>\n    class: <Function> MyClass(0) <function>\n    instance: <MyClass> <object> {\n        variable: 1 <number>\n    }\n    buf: <Buffer 54 68 69 73 20 69 73 20 61 20 62 75 66 66 65 72 21> <Buffer>(17)\n    c: "3" <string>(1) <-conf -enum -w>\n    d: <getter/setter> {\n        get: <Function> (anonymous)(0) <function>\n        set: <Function> (anonymous)(1) <function>\n    }\n}\n' ) ;
//console.log( string.inspect( { style: 'color' } , object ) ) ;