path parameter of require() in node.js

user_11317958 0
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I am learning node.js

for example, I try

var server = require("./myserver.js");

and

var server = require("./myserver");

why do both work? What is this kind of things call?

node.js syntax
1 Answers

If you take a look at node's source code for the require-function, you can see that require's load-function calls a function findLongestRegisteredExtension to determine the file-extension. This function returns .js as its default value if no extension could be determined:

function findLongestRegisteredExtension(filename) {
  const name = path.basename(filename);
  let currentExtension;
  let index;
  let startIndex = 0;
  while ((index = name.indexOf('.', startIndex)) !== -1) {
    startIndex = index + 1;
    if (index === 0) continue; // Skip dotfiles like .gitignore
    currentExtension = name.slice(index);
    if (Module._extensions[currentExtension]) return currentExtension;
  }
  return '.js';
}

That's why using both require("./myserver.js"); or require("./myserver"); will resolve the same module.

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