@harbr/linkprop

linkProp ·

Contains methods for linking properties of dom elements with other dom elements.

Examples are using LitElement.

Installation

npm install @harbr/linkProp

Methods

• linkProp(element, prop, path?)
• linkSiblingProp(host, querySelector, prop, path?)
• linkVal(element, path)
• linkChecked(element, path)

A Note on path

The path is the property path to set on the target element. If ommited the prop value will be used.

Path can be used to set deep properties so it can be something like: state.someObject.someProperty.

Usage

linkProp

The linkProp method links two element properties; usually from a child element to a parent element.

class LinkPropTest extends LitElement {

    @property({type: Object})
    state = {foo: "bar"};

    render() {
        return html`
            <div id="testDiv" 
                @state-changed="${linkProp(this, "state")}"
                @state-path-changed="${linkProp(this, "foo", "state.foo")}"
            >
        `;
    }

    testMethod() {
        const testDiv = this.shadowRoot.querySelector("#testDiv");
        testDiv.state = {foo: "updated!"};
        testDiv.dispatchEvent(new CustomEvent("state-changed"));
        // this.state.foo === "updated!";

        testDiv.foo = "updated using a state path!";
        testDiv.dispatchEvent(new CustomEvent("state-path-changed"));
        // this.state.foo === "updated using a state path!";
    }
}

linkSiblingProp

The linkSiblingProp method links two elements properties that are in the same shadowRoot.

class LinkPropTest extends LitElement {

    render() {
        return html`
            <div id="firstElement"
                test-prop="initial value"
                @test-prop-changed="${linkSiblingProp(this, "#secondElement", "test-prop")}"
            >
            <div id="secondElement">
        `;
    }

    testMethod() {
        const firstElement = this.shadowRoot.querySelector("#firstElement");
        firstElement.setAttribute("test-prop", "updated value!");
        firstElement.dispatchEvent(new CustomEvent("test-prop-changed"));
        // #secondElement.test-prop === "updated value!"
    }
}

linkVal

This is the same as linkProp but it uses "value" as the property to set. This is useful for linking input values.

linkChecked

This is the same as linkProp but it uses "checked" as the property to set. This is useful for linking checkbox values.