JS Design Patterns: Composite, see more at: https://medium.com/p/70d274591b11

DESIGN_PATTERNS_directoryListWithComposite.js

class Directory {
  constructor(name) {
    this.setName(name);
    this.children = [];

    return this;
  }

  add(element) {
    this.children.push(element);
    return this;
  }

  remove(element) {
    this.children = this.children.filter(child => child !== element);
    return this;
  }

  getChild(index) {
    return this.children[index];
  }

  setName(name) {
    this.name = name;
    return this;
  }

  setContent(content) {
    this.content = content;
    return this;
  }

  fill(number, symbol) {
    return [...Array(number)].reduce(accummulator => `${accummulator}-`, "");
  }

  display(level = 0) {
    // const test = this.content.map(content => content.display());

    const nextLevel = level + 1;

    const innerContent = this.children.reduce(
      (accummulator, content) =>
        `${accummulator} \n ${content.display(nextLevel)}`,
      "",
    );

    return `${this.fill(level, "-")} ${this.name} ${innerContent}`;
  }
}

class File {
  constructor(name) {
    this.setName(name);
  }

  add() {}
  remove() {}
  getChild() {}

  setName(name) {
    this.name = name;
  }

  fill(number, symbol) {
    return [...Array(number)].reduce(accummulator => `${accummulator}-`, "");
  }

  display(level = 0) {
    return `${this.fill(level, "-")} ${this.name}`;
  }
}

const run = () => {
  const file1 = new File("file 1");
  const file2 = new File("file 2");
  const file3 = new File("file 3");
  const file4 = new File("file 4");
  const file5 = new File("file 4");

  const subDirectoryWithFile1 = new Directory("subdir1").add(file3);
  const subDirectoryWithFile2 = new Directory("subdir2").add(file4).add(file5);

  const directoryTree = new Directory("directory1")
    .add(file1)
    .add(file2)
    .add(subDirectoryWithFile1)
    .add(subDirectoryWithFile2);

  console.log(directoryTree.display());
  console.log("****************************************");

  directoryTree.remove(file1);

  console.log(directoryTree.display());

  console.log("**************** WITHOUT subdir1 ************************");

  directoryTree.remove(subDirectoryWithFile1);

  console.log(directoryTree.display());
};

run();