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    String.format for JavaScript

    Build Status npm

    Copyright (c) 2009-2017 Daniel Mester Pirttijärvi

    Fork by Georgii Dolzhykov


    This is a JavaScript library for string, date and number formatting. Formatting is done with format strings and is almost completely compatible with the String.Format method in Microsoft .NET Framework.

    The goal of this fork is to add support for Node.js and to explore compatibility with .NET.

    Links to the original library: home page with usage examples, repo.

    Reference information regarding .NET format strings

    In the browser

    To use the library, include the library itself and optionally the cultures you are targeting. Note that if no culture files are included, the invariant culture will be used.

    <script src="sffjs.min.js"></script>
    <script src="cultures/stringformat.en.js"></script>
    <script src="cultures/"></script>

    Then you're ready to go.

    String.format("Welcome back, {0}! Last seen {1:M}", "John Doe", new Date(1985, 3, 7, 12, 33));
    // Outputs:
    // Welcome back, John Doe! Last seen April 07

    By default the browser culture will be used, given that the appropriate culture file has been referenced from the page. To set culture explicitly, use the sffjs.setCulture method, which accepts a IETF language code.



    var sffjs = require('sffjs');
    console.log(sffjs("Welcome back, {0}! Last seen {1:M}", "John Doe", new Date(1985, 3, 7, 12, 33)));
    // Outputs:
    // Welcome back, John Doe! Last seen April 07

    Built-in objects aren't modified unless you explicitly call sffjs.unsafe().

    console.log(typeof String.format);
    // undefined
    console.log(typeof String.format);
    // function

    Cultures are loaded automatically by the setCulture method. There is no need to require them.

    console.log(sffjs("{0:N} -- {1:M}", 1234.567, new Date(1985, 3, 7, 12, 33)));
    // 1,234.57 -- April 07
    console.log(sffjs("{0:N} -- {1:M}", 1234.567, new Date(1985, 3, 7, 12, 33)));
    // 1.234,57 -- 07 Nisan

    Compatibility with .NET

    The output of this library is highly compatible with the output from the .NET implementation. In this section differences will be listed

    • Date format

      • Date format specifier O is not supported
      • Date format specifier R is not supported
    • Number format

      • Number format specifier c ignores specified precision
      • Number format specifier G formats the number according to how a double is formatted in .NET. Other numeric data type are formatted differently in .NET.

    Other types don't have a format implementation, and are thus serialized to a string by the __Format function or the Javascript runtime using the toString function.

    These are additions in this implementation, and thus not supported by the .NET implementation:

    • Object paths/named parameters (String.format('Hello, {}', { user: { name: 'John' } })).


    npm i sffjs

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