JavaScript Import Meta 环境检测：运行时上下文分析

            
// my-module.js
async function loadConfig() {
  const moduleURL = new URL(import.meta.url);
  const configURL = new URL('./config.json', moduleURL);
  const response = await fetch(configURL);
  const config = await response.json();
  return config;
}

loadConfig().then(config => {
  console.log('Configuration:', config);
});

            

              
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// Browser environment
console.log('Module URL:', import.meta.url);

// Attempt to access a non-standard property (may result in undefined)
console.log('Custom Property:', import.meta.customProperty);

            

              
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// Node.js environment (ESM)
console.log('Module URL:', import.meta.url);
console.log('Module Resolve:', import.meta.resolve('./another-module.js')); // Resolves the path to another-module.js

            

              
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function getRuntime() {
  if (typeof window !== 'undefined') {
    return 'browser';
  } else if (typeof process !== 'undefined' && process.versions && process.versions.node) {
    return 'node';
  } else if (typeof Deno !== 'undefined') {
    return 'deno';
  } else {
    return 'unknown';
  }
}

function detectEnvironment() {
  const runtime = getRuntime();

  if (runtime === 'browser') {
    console.log('Running in a browser environment.');
  } else if (runtime === 'node') {
    console.log('Running in a Node.js environment.');
  } else if (runtime === 'deno') {
    console.log('Running in a Deno environment.');
  } else {
    console.log('Running in an unknown environment.');
  }

  console.log('import.meta.url:', import.meta.url);

  try {
    console.log('import.meta.resolve:', import.meta.resolve('./another-module.js'));
  } catch (error) {
    console.log('import.meta.resolve not supported in this environment.');
  }
}

detectEnvironment();

            

              
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// config-loader.js
async function loadConfig() {
  let configURL;

  if (typeof window !== 'undefined') {
    // Browser environment
    configURL = './config/browser.json';
  } else if (typeof process !== 'undefined' && process.versions && process.versions.node) {
    // Node.js environment
    configURL = './config/node.json';
  } else {
    // Default configuration
    configURL = './config/default.json';
  }

  const absoluteConfigURL = new URL(configURL, import.meta.url);
  const response = await fetch(absoluteConfigURL);
  const config = await response.json();
  return config;
}

loadConfig().then(config => {
  console.log('Loaded configuration:', config);
});

            

              
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// module-loader.js
async function loadEnvironmentSpecificModule() {
  let modulePath;

  if (typeof window !== 'undefined') {
    // Browser environment
    modulePath = './browser-module.js';
  } else if (typeof process !== 'undefined' && process.versions && process.versions.node) {
    // Node.js environment
    modulePath = './node-module.js';
  } else {
    console.log('Unsupported environment.');
    return;
  }

  const absoluteModulePath = new URL(modulePath, import.meta.url).href;
  const module = await import(absoluteModulePath);
  module.default(); // Assuming the module exports a default function
}

loadEnvironmentSpecificModule();

            

              
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