JSPM – printf@0.1.2

Package Exports

printf

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (printf) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

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A complete implementation of the printf C functions family for Node.JS, written in pure JavaScript.
The code is strongly inspired by the one available in the Dojo Toolkit.

Bonus! You get extra features, like the %O converter (which inspects the argument). See Extra Features below.

Installing

Via NPM:

$ npm install printf

Usage

Use it like you would in C (printf/sprintf):

var printf = require('printf');
var result = printf(format, args...);

It can also output the result for you, as fprintf:

var printf = require('printf');
printf(write_stream, format, args...);

Features

Flags

(space)

assert.eql('  -42', printf('% 5d', -42));

`+` (plus)

assert.eql('  +42', printf('%+5d', 42));

`0` (zero)

assert.eql('00042', printf('%05d', 42));

`-` (minus)

assert.eql('42   ', printf('%-5d', 42));

Width / precision

assert.eql('42.90', printf('%.2f', 42.8952));
assert.eql('042.90', printf('%06.2f', 42.8952));

Numerical bases

assert.eql('\x7f', printf('%c', 0x7f));
assert.eql('a', printf('%c', 'a'));
assert.eql('"', printf('%c', 34));

Miscellaneous

assert.eql('10%', printf('%d%%', 10));
assert.eql('+hello+', printf('+%s+', 'hello'));
assert.eql('$', printf('%c', 36));

Extra features!

Inspector

The %O converter will call util.inspect(...) at the argument:

assert.eql("Debug: { hello: 'Node', repeat: false }",
  printf('Debug: %O', {hello: 'Node', "repeat": false})
);
assert.eql("Test: { hello: 'Node' }",
  printf('%2$s: %1$O', {"hello": 'Node'}, 'Test')
);

Important: it's a capital "O", not a zero!

Specifying a precision lets you control the depth up to which the object is formatted:

assert.eql("Debug: { depth0: { depth1_: 0, depth1: [Object] } }",
  printf('Debug: %.1O', {depth0: {depth1: {depth2: {depth3: true}}, depth1_: 0}})
);

You can also use %A instead of %O to disable representation of non-enumerable properties:

assert.eql("With non-enumerable properties: [ 1, 2, 3, 4, 5, [length]: 5 ]",
  printf('With non-enumerable properties: %O', [1, 2, 3, 4, 5])
);
assert.eql("Without non-enumerable properties: [ 1, 2, 3, 4, 5 ]",
  printf('Without non-enumerable properties: %A', [1, 2, 3, 4, 5])
);

Argument mapping

In addition to the old-fashioned n$,
you can use hashes and property names!

assert.eql('Hot Pockets',
  printf('%(temperature)s %(crevace)ss', {
    temperature: 'Hot',
    crevace: 'Pocket'
  })
);
assert.eql('Hot Pockets',
  printf('%2$s %1$ss', 'Pocket', 'Hot')
);

Positionals

Lenght and precision can now be variable:

assert.eql(' foo', printf('%*s', 'foo', 4));
assert.eql('      3.14', printf('%*.*f', 3.14159265, 10, 2));
assert.eql('000003.142', printf('%0*.*f', 3.14159265, 10, 3));
assert.eql('3.1416    ', printf('%-*.*f', 3.14159265, 10, 4));

Development

Tests are executed with Mocha. To install it, simple run npm install, it will install Mocha and its dependencies in your project's node_modules directory.

To run the tests:

npm test

To generate the JavaScript files:

make build

The test suite is run online with Travis against Node.js version 0.6, 0.7, 0.8 and 0.9.

Contributors

David Worms https://github.com/wdavidw
Aluísio Augusto Silva Gonçalves https://github.com/AluisioASG
Xavier Mendez https://github.com/jmendeth
LLeo https://github.com/lleo

printf