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    babel-plugin-transform-function-bind

    6.22.0 • Public • Published

    babel-plugin-transform-function-bind

    Compile the new function bind operator :: to ES5.

    Detail

    obj::func
    // is equivalent to:
    func.bind(obj)
     
    obj::func(val)
    // is equivalent to:
    func.call(obj, val)
     
    ::obj.func(val)
    // is equivalent to:
    func.call(obj, val)

    Try in REPL

    Example

    Basic

    const box = {
      weight: 2,
      getWeight() { return this.weight; },
    };
     
    const { getWeight } = box;
     
    console.log(box.getWeight()); // prints '2'
     
    const bigBox = { weight: 10 };
    console.log(bigBox::getWeight()); // prints '10'
     
    // Can be chained:
    function add(val) { return this + val; }
     
    console.log(bigBox::getWeight()::add(5)); // prints '15'

    [Try in REPL](http://babeljs.io/repl/#?evaluate=true&presets=es2015%2Cstage-0&code=const%20box%20%3D%20%7B%0A%20%20weight%3A%202%2C%0A%20%20getWeight()%20%7B%20return%20this.weight%3B%20%7D%2C%0A%7D%3B%0A%0Aconst%20%7B%20getWeight%20%7D%20%3D%20box%3B%0A%0Aconsole.log(box.getWeight())%3B%20%2F%2F%20prints%20'2'%0A%0Aconst%20bigBox%20%3D%20%7B%20weight%3A%2010%20%7D%3B%0Aconsole.log(bigBox%3A%3AgetWeight())%3B%20%2F%2F%20prints%20'10'%0A%2F%2F%20bigBox%3A%3AgetWeight()%20is%20equivalent%20to%20getWeight.call(bigBox)%0A%0A%2F%2F%20Can%20be%20chained%3A%0Afunction%20add(val)%20%7B%20return%20this%20%2B%20val%3B%20%7D%0A%0Aconsole.log(bigBox%3A%3AgetWeight()%3A%3Aadd(5))%3B%20%2F%2F%20prints%20'15')

    Using with document.querySelectorAll

    It can be very handy when used with document.querySelectorAll:

    const { map, filter } = Array.prototype;
     
    let sslUrls = document.querySelectorAll('a')
                    ::map(node => node.href)
                    ::filter(href => href.substring(0, 5) === 'https');
     
    console.log(sslUrls);

    [Try in REPL](http://babeljs.io/repl/#?evaluate=true&presets=es2015%2Cstage-0&code=%0Aconst%20%7B%20map%2C%20filter%20%7D%20%3D%20Array.prototype%3B%0A%0Alet%20sslUrls%20%3D%20document.querySelectorAll('a')%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%3A%3Amap(node%20%3D%3E%20node.href)%0A%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%20%3A%3Afilter(href%20%3D%3E%20href.substring(0%2C%205)%20%3D%3D%3D%20'https')%3B%0A%0Aconsole.log(sslUrls)%3B%0A)

    document.querySelectorAll returns a NodeList element which is not a plain array, so you normally can't use the map function on it, and have to use it this way: Array.prototype.map.call(document.querySelectorAll(...), node => { ... }). The above code using the :: will work because it is equivalent to:

    const { map, filter } = Array.prototype;
     
    let sslUrls = document.querySelectorAll('a');
    sslUrls = map.call(sslUrls, node => node.href);
    sslUrls = filter.call(sslUrls, href => href.substring(0, 5) === 'https');
     
    console.log(sslUrls);

    Auto self binding

    When nothing is specified before the :: operator, the function is bound to its object:

    $('.some-link').on('click', ::view.reset);
    // is equivalent to:
    $('.some-link').on('click', view.reset.bind(view));

    Installation

    npm install --save-dev babel-plugin-transform-function-bind

    Usage

    Via .babelrc (Recommended)

    .babelrc

    {
      "plugins": ["transform-function-bind"]
    }

    Via CLI

    babel --plugins transform-function-bind script.js

    Via Node API

    require("babel-core").transform("code", {
      plugins: ["transform-function-bind"]
    });

    References

    Keywords

    Install

    npm i babel-plugin-transform-function-bind

    DownloadsWeekly Downloads

    343,671

    Version

    6.22.0

    License

    MIT

    Last publish

    Collaborators

    • hzoo
    • loganfsmyth
    • existentialism