‚̧Nearly Perfect Mediocracy
    Wondering what‚Äôs next for npm?Check out our public roadmap! ¬Ľ

    This package has been deprecated

    Author message:

    This component is deprecated

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


    Published on NPM

    Build Status

    Published on webcomponents.org


    Variables evaluator for Advanced REST Client and API components.

    The element handles evaluate-variable custom event to evaluate a variable against current environment variables.

    The component queries for current environment dispatching environment-current custom event. The event should be handled and values should be set within the same event loop. The handler must set variables property which is an array of variables with the following properties:

      enabled: true,
      variable: 'variable-name',
      value: 'replacement value'

    The evaluate-variable event will have a result property set on the detail object of the event. The property has a promise object resolved to evaluated property.

    const e = new CustomEvent('evaluate-variable', {
      cancelable: true,
      bubbles: true,
      detail: {
        value: 'string with a ${variable}'
    e.detail.result.then((value) => {

    When context property on the detail object is specified then the component skips querying for environment-current and use this value as the context. It is a map for variables with values.

    Additionally the event can carry override property on the detail object. When set the final context values (whether received from environment-current event or via context property) are overwritten values in this map.

    const e = new CustomEvent('evaluate-variable', {
      cancelable: true,
      bubbles: true,
      detail: {
        value: '${a} ${b} ${c}',
        context: {
          a: 'context value a',
          b: 'context value b'
        override: {
          b: 'override value b',
          c: 'override value c'
    e.detail.result.then((value) => {
      // "context value a override value b override value c"

    Jexl dependency

    Previous versions of this component included Jexl library. This version do not have Jexl as a dependency but it is required to run the component.

    You must install Jexl on your project, and build it for browser. See dev-lib/ folder for an example of such a build.

    Finally you have to either pass the pointer to Jexl library to jexl property or point to a relative in the window object.

    Setting Jexl reference:

    const eval = document.querySelector('variables-evaluator');
    eval.jexl = myJexlVariable;

    Setting path to Jexl:

    <variables-evaluator jexlpath="ArcVariables.JexlDev"></variables-evaluator>

    This expects the Jexl library to be under window.ArcVariables.JexlDev variable.



    npm install --save @advanced-rest-client/variables-evaluator

    In an html file

        <script type="module">
          import '@advanced-rest-client/variables-evaluator/variables-evaluator.js';
        <script src="jexl.min.js"></script> 
        <variables-evaluator jexlpath="jexl"></variables-evaluator>

    In a LitElement template

    import { LitElement, html } from 'lit-element';
    import '@advanced-rest-client/variables-evaluator/variables-evaluator.js';
    class SampleElement extends LitElement {
      render() {
        return html`
        <variables-evaluator jexl="${this.jexlRef}"></variables-evaluator>
      async evaluate() {
        const node = this.shadowRoot.querySelector('variables-evaluator');
        // clears previously set context and cache
        const result = await element.evaluateVariable('some ${str}', {
          str: 'value'
        console.log(result); // some value
    customElements.define('sample-element', SampleElement);


    git clone https://github.com/advanced-rest-client/variables-evaluator
    cd variables-evaluator
    npm install

    Running the demo locally

    npm start

    Running the tests

    npm test


    npm i @advanced-rest-client/variables-evaluator

    DownloadsWeekly Downloads






    Unpacked Size

    98.4 kB

    Total Files


    Last publish


    • avatar
    • avatar
    • avatar
    • avatar