deepCopy.js

/**
 * 对象深拷贝
 */
function deepCopy (object, pairs = []) {
  let copy = {};
  pairs.push([object, copy]);
  for (let key in object) {
    if (object.hasOwnProperty(key)) {
      let value = object[key];
      if (Array.isArray(value)) {
        value = value.slice();
      }
      if ("[object Object]" === Object.prototype.toString.call(value)) {
        let exsit = false;
        for (let i = 0, pair = null; pair = pairs[i]; i++) {
          if (value === pair[0]) {
            value = pair[1];
            exsit = true;
            break;
          }
        }
        if (!exsit) {
          value = deepCopy(value, pairs);
        }
      }
      copy[key] = value;
    }
  }
  return copy;
}

test.js

let root = {
  name: "root",
  array: [0],
  function (v) { this.array.push(v) },
};
root.child = {
  name: "child",
  parent: root,
};
root.grandchild =
root.child.child = {
  name: "grandchild",
  grandparent: root,
  parent: root.child,
};
root.self = root;
root.child.self = root.child;
root.grandchild.self = root.grandchild;

let copy = deepCopy(root);
copy.child.parent.array.push(1);
copy.self.name = "root copy";
copy.child.name = "child copy";
copy.child.child.name = "grandchild copy";

console.log(root);
console.log(copy);