nemtsov/remove-unused-imports.js

## remove-unused-imports.js
module.exports = (file, api, options) => {
  const j = api.jscodeshift;

  const printOptions = options.printOptions || {quote: 'single'};
  const root = j(file.source);
  const requires = {};

  const filterAndTransformRequires = path => {
    const varName = path.value.local.name;
    const scopeNode = path.parentPath.scope.node;
    const importPath = path.parentPath.parentPath;

    // Check if we already have a require for this, if we do just use
    // that one.
    if (
      requires[varName] &&
      requires[varName].scopeNode === scopeNode
    ) {
      j(importPath).remove();
      return true;
    }

    // We need this to make sure the JSX transform can use `React`
    if (varName === 'React') {
      return false;
    }

    // Remove required vars that aren't used.
    const usages = j(path)
      .closestScope()
      .find(j.Identifier, {name: varName})
      .filter(p => p.value !== path.value.local)
      .filter(p => !(p.parentPath.value.type === 'Property' && p.name === 'key'))
      .filter(p => p.name !== 'property')

    if (!usages.size()) {
      j(importPath).remove();
      return true;
    }

    requires[varName] = {scopeNode, varName};
  };

  const didTransform = root
    .find(j.ImportDefaultSpecifier)
    .filter(filterAndTransformRequires)
    .size() > 0;

  return didTransform ? root.toSource(printOptions) : null;
};