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    lines-builder
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    1.3.1 • Public • Published

    lines-builder

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    Tool and model to handle string lines and indentation.

    Usage

    To create a new lines-builder object:

    import { lines } from "lines-builder";
    
    const l = lines("Hello World\nThis is the 2nd line");
    console.log(l);
    // Hello World
    // This is the 2nd line

    lines accepts an optional options object and any additional string (or lines-builder) as lines.

    Options

    Option Type Description Default
    indent string|number The indentation to use to indent the lines (exact string or the number of spaces). null (no indentation)
    indentEmpty boolean Whether the empty lines should still be indented. false
    skipFirstLevelIndent boolean Whether only the nested lines-builders should be indented. false
    skipEmpty boolean Whether empty lines should be added to the output string. false
    trimLeft boolean Can trailing white spaces be trimmed from the parsed lines. true
    trimRight boolean Can leading white spaces be trimmed from the parsed lines. true
    eol string The line-break to be used. If not set, it is determined based on the platform. null

    Append

    You can append any lines, including new line to the end (in place), passing any string (or lines-builder) as arguments to append :

    l.append("3rd line", null, "4th line\nand 5th line");
    console.log(l);
    // Hello World
    // This is the 2nd line
    // 3rd line
    // 
    // 4th line
    // 5th line

    Prepend

    You can prepend any lines, including new-line to the beginning (in place), passing any string (or lines-builder) as arguments to prepend :

    l.prepend("This is the title", null, "And the 0th line");
    console.log(l);
    // This is the title
    // 
    // And the 0th line
    // Hello World
    // This is the 2nd line
    // 3rd line
    // 
    // 4th line
    // 5th line

    Indent

    You can set a global indentation to the lines added:

    const l = lines({ indent: '--' }, "Hello World", "2nd line");
    console.log(l);
    // --Hello World
    // --2nd line

    By default, no indentation is set.

    You can also set a number as the indentation. In this case, the given number of spaces will be used.

    Trim

    By default, lines-builder trims the leading and trailing whitespaces, but you can turn it off:

    const l = lines({ trimLeft: false, trimRight: false }, "Hello World  ", "  2nd line\n  3rd line");
    console.log(l);
    // Hello World
    //   2nd line
    //   3rd line

    Nesting

    Lines-builder accepts another lines-builder instance instead of any string lines, to be able to nest it:

    const nested = lines({ indent: '==' }, "1st nested", "2nd nested");
    const parent = lines({ indent: '--' }, "1st parent", nested, "2nd parent");
    console.log(parent);
    // --1st parent
    // --==1st nested
    // --==2nd nested
    // --2nd parent

    By setting the skipFirstLevelIndent option, the lines-builder won't indent the direct lines of the lines-builder, only starting from the nested ones:

    const nested = lines(, "1st nested", "2nd nested");
    const parent = lines({ skipFirstLevelIndent: true, indent: '--' }, "1st parent", nested, "2nd parent");
    console.log(parent);
    // 1st parent
    // --1st nested
    // --2nd nested
    // 2nd parent

    Default options

    As seen above, options can be set per each lines-builder, but if you want to use one set of options, per each lines-builder you will use, you can use the setDefaultOptions .

    import { lines, setDefaultOptions } from "lines-builder";
    
    setDefaultOptions({ indent: "__" });
    
    const nested = lines("1st nested", "2nd nested");
    const parent = lines("1st parent", nested, "2nd parent");
    console.log(parent);
    // __1st parent
    // ____1st nested
    // ____2nd nested
    // __2nd parent

    Note that the default options can be reset to the initial ones with the resetDefaultOptions .

    EOL

    To output/format the lines, the lines-builder will determine the appropriate EOL based on the platform used ( \r\n for Windows, \n for other OS). If you need to set explicitly what EOL to use, pass it in any options:

    // IBM Mainframe EOL
    const l = lines({ eol: "\025" }, "Hello", "World");
    console.log(l);
    // Hello\025World

    Filtering

    The filter method can be used to filter in place - either to keep or remove lines matching a specific pattern.

    const l = lines("simple line", "# comment line", "other line");
    // the following expression removes lines starting with #
    l.filter(/^\s*#/, true);
    console.log(l);
    // simple line
    // other line

    The filter function accepts either

    1. a string, what will be converted to a case-insensitive RegExp
    2. a RegExp, what will be used as it is
    3. a type LineMatcher = (line: string, i: number) => boolean; function, what should return true in case of a match.

    The filter function, based on the reverse parameter

    1. if false, it keeps the line if the matcher is true; otherwise, it removes it
    2. if true, it removes the line if the matcher is true; otherwise, it removes it

    In the case of nested lines-builder, the same matcher and parameter are applied, and the nested one is kept if it contains any line after the filter.

    Other

    For detailed documentation see the TypeDocs documentation.

    This package uses debug for logging, use lines-builder to see debug logs:

    DEBUG=lines-builder node my-script.js

    Install

    npm i lines-builder

    DownloadsWeekly Downloads

    7,718

    Version

    1.3.1

    License

    MIT

    Unpacked Size

    22 kB

    Total Files

    5

    Last publish

    Collaborators

    • szikszail