Polymer 3 Code Template for WebStom, PhpStorm, All JetBrains IDE

polymer-3-lit-template.js

#set($CLASS_NAME = "")
#set($part = "")
#if($NAME.endsWith(".js"))
    #set($end = $NAME.length() - 3)
    #set($NAME = "$NAME.substring(0,$end)")
#end
#foreach($part in $NAME.split("-"))
    #set($CLASS_NAME = "${CLASS_NAME}$part.substring(0,1).toUpperCase()$part.substring(1).toLowerCase()")
#end
import { LitElement, html } from 'lit-element/lit-element.js';

class ${CLASS_NAME} extends LitElement {
    constructor() {
        super();
        // Default properties can be set from the element's constructor
        this.mood = "Hello ${NAME}"
      }
    
    static get properties() {
        return {
            mood: String
        };
    }
    
    render() {
        return html`
            <style>
                :host {
                    display: block;
                }
            </style>
            <div>Lit-element! ${this.mood}!</div>
        `;
    }
}

window.customElements.define('${NAME}', ${CLASS_NAME});

polymer-3-template.js

#set($CLASS_NAME = "")
#set($part = "")
#if($NAME.endsWith(".js"))
    #set($end = $NAME.length() - 3)
    #set($NAME = "$NAME.substring(0,$end)")
#end
#foreach($part in $NAME.split("-"))
    #set($CLASS_NAME = "${CLASS_NAME}$part.substring(0,1).toUpperCase()$part.substring(1).toLowerCase()")
#end
import { PolymerElement, html } from '@polymer/polymer/polymer-element.js';

class ${CLASS_NAME} extends PolymerElement {
    static get properties() {
        return {};
    }
    
    static get template() {
        return html`
            <style>
                :host {
                    display: block;
                }
            </style>
            <div>Hola mundo! Polymer 3</div>
        `;
    }
}

window.customElements.define('${NAME}', ${CLASS_NAME});

Add in
Settings > Editor > File and code Templates

now simply
right click in folder > new > [Name of your template]

Name: "my-element"

Edited

Change _render to render