Google Maps API v3: How to remove all markers?

Central marker control zone

Now, let's enhance that initial quick fix by crafting a centralized marker management system to maintain a vice-like grip on your map's markers. Here are three master functions to do just that:

var markersArray = [];  // Our marker congregation area

// Task: Add a fellow marker to this world
function addMarker(location) {
  var marker = new google.maps.Marker({ position: location, map: map });
  markersArray.push(marker);  // Welcome onboard, mate!
}

// Who's on the map? Let's meet 'em!
function getMarkers() {
  return markersArray;  // Here they are, the gangs all here.
}

// Sorry guys, it's doomsday!
function clearMarkers() {
  markersArray.forEach(marker => marker.setMap(null));  // THHHHANOS Snap!
  markersArray.length = 0;  // You see nothing here!
}
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Map extension - smooth operator

For a more holistic shield, we extend the google.maps.Map prototype. This encapsulates the function, preventing any unwanted global namespace squabble. Behold:

google.maps.Map.prototype.clearOverlays = function() {
  while(this.markersArray.length) {
    // Oh look, they're dropping like flies!
    this.markersArray.pop().setMap(null);
  }
};

// Usage:
map.markersArray = [];  // Make some room on the map, guys!
map.clearOverlays();    // And... they're gone! *Poof*
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Stay sharp! Remember to tread this path cautiously, as Google's future updates could accidentally strike your extensions if they meddle with their own naming conventions or tweak their existing structure.

Large marker crowd? - handle with caution

Hosting a large marker posse on your map? You might face performance snags when you attempt to shoo them all away at once. Restructure your tactic slightly:

function clearMarkersBatch() {
  var batchInterval = setInterval(function() {
    if (!markersArray.length) {
      clearInterval(batchInterval);
      // Peace at last!
      batchInterval = null;
      return;
    }
    var marker = markersArray.pop();  // Here goes another.
    marker.setMap(null);  // Adios, amigo!
  }, 16); // We're aiming for, roughly, 60fps here!
}
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By staggering your marker wipe-out operations, it augments performance, reducing UI freezing or slowdown chances even on devices that claim to have the 'muscle power' of a hamster.

A checklist for likely challenges

As your map cleans up its marker act, stay alert & nip potential issues in the bud:

• Memory leaks: Don't let markers litter your memory - ensure all references are discarded.
• Event listeners: Cut loose any event listeners tied to markers before ushering them off the map.
• Map references: Double check the marker's map association before asserting setMap(null) - we don't want unnecessary errors!

Beginner's Video Tutorial

A video guide particularly comes of aid for beginners!

1. Stitch a YouTube video that vividly demonstrates the steps.
2. Employ animated graphics or actual screen recordings to drive home the process.
3. Ensure narration or subtitles accompany it to make it accessible to everyone.

Visual instructions can be the ultimate saviour for many beginners.

Verifying performance

Tighten your code's performance by reviewing it:

• Apply Chrome's DevTools to garner insights on performance.
• Be on the lookout for potential memory leaks, excess DOM manipulations, or CPU being overworked.

After all, a code that performs is the one that wins!