string-format is a small JavaScript library for formatting strings, based on
Python's str.format(). For example:
'"{firstName} {lastName}" <{email}>'.format(user)
// => '"Jane Smith" <[email protected]>'The equivalent concatenation:
'"' + user.firstName + ' ' + user.lastName + '" <' + user.email + '>'
// => '"Jane Smith" <[email protected]>'-
Install:
$ npm install string-format -
Require:
var format = require('string-format')
-
Define
window.format:<script src="path/to/string-format.js"></script>
string-format can be used in two modes: function mode and method mode.
format('Hello, {}!', 'Alice')
// => 'Hello, Alice!'In this mode the first argument is a template string and the remaining arguments are values to be interpolated.
'Hello, {}!'.format('Alice')
// => 'Hello, Alice!'In this mode values to be interpolated are supplied to the format method
of a template string. This mode is not enabled by default. The method must
first be defined via format.extend:
format.extend(String.prototype, {})format(template, $0, $1, …, $N) and template.format($0, $1, …, $N) can then
be used interchangeably.
Returns the result of replacing each {…} placeholder in the template string
with its corresponding replacement.
Placeholders may contain numbers which refer to positional arguments:
'{0}, you have {1} unread message{2}'.format('Holly', 2, 's')
// => 'Holly, you have 2 unread messages'Unmatched placeholders produce no output:
'{0}, you have {1} unread message{2}'.format('Steve', 1)
// => 'Steve, you have 1 unread message'A format string may reference a positional argument multiple times:
"The name's {1}. {0} {1}.".format('James', 'Bond')
// => "The name's Bond. James Bond."Positional arguments may be referenced implicitly:
'{}, you have {} unread message{}'.format('Steve', 1)
// => 'Steve, you have 1 unread message'A format string must not contain both implicit and explicit references:
'My name is {} {}. Do you like the name {0}?'.format('Lemony', 'Snicket')
// => ValueError: cannot switch from implicit to explicit numbering{{ and }} in format strings produce { and }:
'{{}} creates an empty {} in {}'.format('dictionary', 'Python')
// => '{} creates an empty dictionary in Python'Dot notation may be used to reference object properties:
var bobby = {firstName: 'Bobby', lastName: 'Fischer'}
var garry = {firstName: 'Garry', lastName: 'Kasparov'}
'{0.firstName} {0.lastName} vs. {1.firstName} {1.lastName}'.format(bobby, garry)
// => 'Bobby Fischer vs. Garry Kasparov'0. may be omitted when referencing a property of {0}:
var repo = {owner: 'davidchambers', slug: 'string-format'}
'https://github.com/{owner}/{slug}'.format(repo)
// => 'https://github.com/davidchambers/string-format'If the referenced property is a method, it is invoked with no arguments to determine the replacement:
var sheldon = {
firstName: 'Sheldon',
lastName: 'Cooper',
dob: new Date('1970-01-01'),
fullName: function() { return '{firstName} {lastName}'.format(this) },
quip: function() { return 'Bazinga!' }
}
'{fullName} was born at precisely {dob.toISOString}'.format(sheldon)
// => 'Sheldon Cooper was born at precisely 1970-01-01T00:00:00.000Z'
"I've always wanted to go to a goth club. {quip.toUpperCase}".format(sheldon)
// => "I've always wanted to go to a goth club. BAZINGA!"This function takes a prototype (presumably String.prototype) and an object
mapping names to transformers, and defines a format method on the prototype.
A transformer is applied if its name appears, prefixed with !, after a field
name in a template string.
format.extend(String.prototype, {
escape: function(s) {
return s.replace(/[&<>"'`]/g, function(c) {
return '&#' + c.charCodeAt(0) + ';'
})
},
upper: function(s) { return s.toUpperCase() }
})
'Hello, {!upper}!'.format('Alice')
// => 'Hello, ALICE!'
var restaurant = {
name: 'Anchor & Hope',
url: 'http://anchorandhopesf.com/'
}
'<a href="{url!escape}">{name!escape}</a>'.format(restaurant)
// => '<a href="http://anchorandhopesf.com/">Anchor & Hope</a>'$ npm install
$ npm test
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