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    with
    TypeScript icon, indicating that this package has built-in type declarations

    7.0.2 • Public • Published

    with

    Compile time with for strict mode JavaScript

    Build Status Rolling Versions NPM version

    Installation

    $ npm install with
    

    Usage

    var addWith = require('with');
     
    addWith('obj', 'console.log(a)');
    // => ';(function (console, a) {
    //       console.log(a)
    //     }("console" in obj ? obj.console :
    //                          typeof console!=="undefined" ? console : undefined,
    //       "a" in obj ? obj.a :
    //                    typeof a !== "undefined" ? a : undefined));'
     
    addWith('obj', 'console.log(a)', ['console']);
    // => ';(function (console, a) {
    //       console.log(a)
    //     }("a" in obj ? obj.a :
    //                    typeof a !== "undefined" ? a : undefined));'

    API

    addWith(obj, src[, exclude])

    The idea is that this is roughly equivallent to:

    with (obj) {
      src;
    }

    There are a few differences though. For starters, assignments to variables will always remain contained within the with block.

    e.g.

    var foo = 'foo';
    with ({}) {
      foo = 'bar';
    }
    assert(foo === 'bar'); // => This fails for compile time with but passes for native with
     
    var obj = {foo: 'foo'};
    with ({}) {
      foo = 'bar';
    }
    assert(obj.foo === 'bar'); // => This fails for compile time with but passes for native with

    It also makes everything be declared, so you can always do:

    if (foo === undefined)

    instead of

    if (typeof foo === 'undefined')

    This is not the case if foo is in exclude. If a variable is excluded, we ignore it entirely. This is useful if you know a variable will be global as it can lead to efficiency improvements.

    It is also safe to use in strict mode (unlike with) and it minifies properly (with disables virtually all minification).

    Parsing Errors

    with internally uses babylon to parse code passed to addWith. If babylon throws an error, probably due to a syntax error, addWith returns an error wrapping the babylon error, so you can retrieve location information. error.component is "src" if the error is in the body or "obj" if it's in the object part of the with expression. error.babylonError is the error thrown from babylon.

    License

    MIT

    Keywords

    none

    Install

    npm i with

    DownloadsWeekly Downloads

    1,317,199

    Version

    7.0.2

    License

    MIT

    Unpacked Size

    40.3 kB

    Total Files

    22

    Last publish

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