在wordpress插件中可视化图形

Question

I'm a novice in php and WordPress. I'm trying to understand how to display a graph generated in html an JavaScript in a basic WordPress plugin.

This is the basic admin page where I would like the graph to be displayed.

<?php
/*
Plugin Name: Test plugin
Description: A test plugin to demonstrate wordpress functionality
Author: the author
Version: 0.1
*/
add_action('admin_menu', 'test_plugin_setup_menu');

function test_plugin_setup_menu(){
        add_menu_page( 'Test Plugin Page', 'Test Plugin', 'manage_options', 'test-plugin', 'test_init' );
}

function test_init(){
        echo "<h1>Hello World!</h1>";
}

?>

For example, I will use chart.js for the plot with a file for the html and another one for the JavaScript.

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js"></script>

<canvas id="bar-chart" width="800" height="450"></canvas>

JavaScript

 // Bar chart
new Chart(document.getElementById("bar-chart"), {
    type: 'bar',
    data: {
      labels: ["Africa", "Asia", "Europe", "Latin America", "North America"],
      datasets: [
        {
          label: "Population (millions)",
          backgroundColor: ["#3e95cd", "#8e5ea2","#3cba9f","#e8c3b9","#c45850"],
          data: [2478,5267,734,784,433]
        }
      ]
    },
    options: {
      legend: { display: false },
      title: {
        display: true,
        text: 'Predicted world population (millions) in 2050'
      }
    }
});

Answer 1

This would be the simplest solution, enqueuing Chart.js and printing the script to start it inside the menu HTML output:

add_action('admin_menu', 'test_plugin_setup_menu');

function test_plugin_setup_menu(){
    add_menu_page( 'Test Plugin Page', 'Test Plugin', 'manage_options', 'test-plugin', 'test_init' );
}

function test_init(){
    wp_enqueue_script( 'chart-js', '//cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.min.js' );
    echo "<h1>Hello World!</h1>";
    ?>
    <canvas id="bar-chart" width="800" height="450"></canvas>
    <script>
        window.onload = function(){
            new Chart(document.getElementById("bar-chart"), {
                type: 'bar',
                data: {
                  labels: ["Africa", "Asia", "Europe", "Latin America", "North America"],
                  datasets: [
                    {
                      label: "Population (millions)",
                      backgroundColor: ["#3e95cd", "#8e5ea2","#3cba9f","#e8c3b9","#c45850"],
                      data: [2478,5267,734,784,433]
                    }
                  ]
                },
                options: {
                  legend: { display: false },
                  title: {
                    display: true,
                    text: 'Predicted world population (millions) in 2050'
                  }
                }
            });
        };
    </script>
    <?php
}

But I'd suggest doing it on a standard fashion and load Chart.js and your own JavaScript file conditionally to your menu page, as shown at How do I Enqueue styles/scripts on Certain /wp-admin Pages?