How to auto fill the shipping address field

Question

I'm a beginner magento 2 user. Now, I want to set some default value in the shipping address's field, could you teach me what should I do? What file should I need to code?

Thank very much.

The below image is my expect result:

Answer 1

In that case you need a plugin for this.

Create di.xml [Vendor/Module/etc/frontend/di.xml]

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Checkout\Block\Checkout\LayoutProcessor">
        <plugin name="vendor_assign_default_value" type="Vendor\Module\Plugin\Checkout\Model\Checkout\LayoutProcessor" sortOrder="100"/>
    </type>
</config>

Create LayoutProcessor.php [Vendor/Module/Plugin/Checkout/Model/Checkout/LayoutProcessor.php]

namespace Vendor\Module\Plugin\Checkout\Model\Checkout;


class LayoutProcessor
{
    /**
     * @param \Magento\Checkout\Block\Checkout\LayoutProcessor $subject
     * @param array $jsLayout
     * @return array
     */
    public function afterProcess(
        \Magento\Checkout\Block\Checkout\LayoutProcessor $subject,
        array  $jsLayout
    ) {
        $jsLayout['components']['checkout']['children']['steps']['children']['shipping-step']['children']
        ['shippingAddress']['children']['shipping-address-fieldset']['children']['firstname']['value'] = 'FirstName';

        $jsLayout['components']['checkout']['children']['steps']['children']['shipping-step']['children']
        ['shippingAddress']['children']['shipping-address-fieldset']['children']['company']['value'] = 'Demo Company';
        return $jsLayout;
    }
}