Parses friends of your friends and show you links profiles with people you may know. Usage: open your friends page, open dev tools, copypaste the script to console, press enter and wait. You may watch the downloading process on networks tab.

myanimelist people you may know.js

const DEPTH = 2;  // 1 is usless, 3 is insane
const PROFILE_RE = /profile\/(.*?)(?:\/|$)/;
const SELF_PROFILE_RE = /profile\/(.*?)\/friends/;
const PROFILE_URL = 'https://myanimelist.net/profile/{profile}';
const FRIENDS_URL = 'https://myanimelist.net/profile/{profile}/friends';

function promiseWhile(condition, action) {
  return new Promise((resolve, reject) => {
    function loop() {
      if (!condition()) {
        return resolve();
      }
      action().then(loop).catch(reject);
    }
    setTimeout(loop, 0);
  });
}

const reduce = Function.bind.call(Function.call, Array.prototype.reduce);
const isEnumerable = Function.bind.call(Function.call, Object.prototype.propertyIsEnumerable);
const concat = Function.bind.call(Function.call, Array.prototype.concat);
const keys = Reflect.ownKeys;

if (!Object.values) {
	Object.values = function values(O) {
		return reduce(keys(O), (v, k) => concat(v, typeof k === 'string' && isEnumerable(O, k) ? [O[k]] : []), []);
	};
}

if (!Object.entries) {
	Object.entries = function entries(O) {
		return reduce(keys(O), (e, k) => concat(e, typeof k === 'string' && isEnumerable(O, k) ? [[k, O[k]]] : []), []);
	};
}

new(class {
  constructor() {
    const self = (window.location.toString().match(SELF_PROFILE_RE) || [null, null])[1];
    if (self === null) {
      throw 'You have to run this script from friends page of someones profile.';
    }
    this.skip = [self];
    this.myFriends = this.parseFriends(document);
    this.friends = this.myFriends;
    // this.friends = this.friends.slice(2, 4);  // for debugging
    this.friendsInCommon = {};
    let level = 0;

    promiseWhile(() => level < DEPTH, () => {
      const fetchPromises = [];
      this.friends.forEach((friend) => {
        if (this.skip.indexOf(friend) === -1) {
          this.skip.push(friend);
          const fetchPromise = fetch(FRIENDS_URL.replace('{profile}', friend));
          fetchPromises.push(Promise.all([fetchPromise.then(r => r.text()), friend]));
        }
      });
      return Promise.all(fetchPromises)
        .then((data) => {
          level += 1;
          data.forEach(([responseText, friend]) => {
            const parser = new DOMParser();
            const dom = parser.parseFromString(responseText, 'text/html');
            const friends = this.parseFriends(dom);
            this.friends = this.friends.concat(friends);
            this.friendsInCommon[friend] = this.getCommonFriendsCount(friends);
          });
        });
    }).then(() => {
      const sortedFriendsInCommon = Object.entries(this.friendsInCommon).sort((a, b) => a[1] - b[1]);
      sortedFriendsInCommon.forEach(([friend, friendsInCommon]) => {
        if (this.myFriends.indexOf(friend) === -1) {
          const profileUrl = PROFILE_URL.replace('{profile}', friend);
          console.log(`${friendsInCommon}\t${profileUrl}`);
        }
      });
    });
  }

  parseFriends(dom) {
    const friends = [];
    dom.querySelectorAll('.friendHolder .friendBlock .friendIcon a[href*="profile/"]')
      .forEach((el) => {
        const friend = el.href.match(PROFILE_RE)[1];
        friends.push(friend);
      });
    return friends;
  }

  getCommonFriendsCount(friends) {
    let commonFriends = 0;
    friends.forEach((friend) => {
        if (this.myFriends.indexOf(friend) !== -1) {
          commonFriends += 1;
        }
      });
    return commonFriends;
  }
})();