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Polymer 1.0 : Custom elements
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polymer-1.0-create-custom-element.md

Polymer 1.0 : Custom elements

Simplest possible workflow

Minimal steps required to create a custom elemenet in Polymer 1.0, without any aid from tools like Yeoman and Gulp.

I have used the Quick tour of Polymer as a reference.

Prerequisites

  • Install Node.
  • Install a light weight HTTP server
    npm install -g serve

Project setup

Description Command_____________________________
Install or update Bower npm install -g bower
npm update -g bower
Create a project folder mkdir my-project
cd my-project
Init a new project with Bower bower init
Install Polymer + web-components bower install --save Polymer/polymer
Create file for the custom element and
append code listed below		 touch greeting-element.html
Create index.html and
append code listed below		 touch index.html
Start the HTTP server serve
... or, if you're on a Mac, you can instead use the python SimpleHttpServer python -m SimpleHTTPServer 3000
Open browser with URL http://localhost:3000/
Output should be Hello Stranger!
Hello Leif!
Updating packages bower update

greeting-element.html

Code to create the custom element.

<link rel="import" href="bower_components/polymer/polymer.html">
<dom-module id="greeting-element">
  <style>
    :host {
      display: block;
    }
    h1 {
      color: blue;
    }
  </style>
  <template>
    <h1>Hello <span>{{greeting}}</span>!</h1>
  </template>
  <script>
    Polymer({
      is: 'greeting-element',

      properties: {
        greeting: {
          type: String,
          value: "Stranger"
        }
      }
    });
  </script>
</dom-module>

index.html

Import the greeting-element, <link rel="import" href="greeting-element.html"></link>, into index.html and start your custom element.

<!DOCTYPE html>
<html>
<head>
  <title>Example Polymer custom element</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, minimum-scale=1.0, initial-scale=1, user-scalable=yes">

  <script src="bower_components/webcomponentsjs/webcomponents-lite.min.js"></script>
  <link rel="import" href="greeting-element.html"></link>
</head>
<body>
  <greeting-element></greeting-element>
  <greeting-element greeting="Leif"></greeting-element>
</body>
</html>

Create Polymer element with Yeoman element generator

Using the Yeoman element generator requires us to follow the folder layout from a Yeoman generated Polymer project. So before we can create a Yeoman element, we must scaffold a new Polymer project using generator-polymer.

As an alternative to using Yeoman to scaffold your project, you can download the Polymer Starter Kit and skip the next section.

Yeoman generator for Polymer projects

generator-polymer is a scaffolding tool for Yeoman, which generates a sample Polymer 1.0 project using Polymer Start Kit, letting you easily create and customize Polymer (custom) elements via the command-line and import them using HTML Imports. This saves you time writing boilerplate code so you can start writing up the logic to your components straight away. Use the following steps to set up a new Polymer app, generating all the boilerplate you need to get started.

Description Command______________________________
Install or update tools npm install -g yo bower grunt-cli
npm update -g yo bower grunt-cli
Install or update gulp npm install -g gulp
npm update -g gulp
Install or update Yeoman generator for Polymer projects npm install -g generator-polymer
npm update -g generator-polymer
Create a project folder mkdir my-project
cd my-project
Sets up a new Polymer app yo polymer
Start the HTTP server gulp serve
Open browser with URL http://localhost:3000/

A short introduction to generator-polymer is provided here: Setting up your Production-ready Polymer 1.0 Application Development

Create Polymer element with Yeoman element generator

Description Command______________________________
Generate element. yo polymer:el yo-greeting-element
The generated element,yo-greeting-element.html is created in folder
./app/elements/yo-greeting-element
If you don't wish to use the standard folder layout, go ahead and move the generated element to another folder (but remember to update the href in line 1 of the generated html).

Create reusable Polymer element with Yeoman seedelement generator

Generates a reusable polymer element based on the seed-element workflow. This should only be used if you're creating a standalone element repo that you intend to share with others via bower. If you're just building a Polymer app, stick to the Element generator.

Description Command______________________________
Install or update tools and Polymer generator npm install -g yo bower grunt-cli
npm update -g yo bower grunt-cli
Install or update Yeoman generator for Polymer projects npm install -g generator-polymer
npm update -g generator-polymer
Create a project folder mkdir my-project
cd my-project
Scaffolding Polymer seed-element yo polymer:seed my-seed-element
Install Polyserve npm install -g polyserve
npm update -g polyserve
Start Polyserve polyserve
Open browser at
localhost:8080/components/my-seed-element/
Publish to reusable element to github

Useful Bower commands

Command_______________________________________ Description
bower init Create new project in working dir
bower install Install package dependencies from bower.json in working dir
bower install polymer --save Polymer + web-components. Always on an new project
bower install polymerelements/paper-elements --save Install and add add package dep to bower.json in working dir,
bower install polymerelements/iron-elements --save All elements in package iron-elements.
bower install --save PolymerElements/paper-button One particular element.
bower info polymerelements/paper-elements Package info
bower info GoogleWebComponents/google-map Component info
bower update Update package dependecies in project
bower uninstall paper-elements --remove Remove package from project
bower uninstall paper-icon-button --remove Remove component from project
bower list polymerelements/paper-elements Show package info
bower list paper-icon-button Show component info
bower search Search bower db for dependency, e.g. bower search jquery
bower prune Uninstall dependencies not listed in bower.json. As an alternative; just delete the bower_components folder and run bower install
bower register <component> git://github.com/<user>/<component>.git Register component, see: http://bower.io/docs/creating-packages/#register
bower info Get info about registered component

Some useful links

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