Script for randomly replacing symbols

It worked. However, one must be wary of Illustrator's symbol naming copy conventions as new symbols get a sequential number on the end of them. When you copy "Symbol 1", it becomes called "Symbol 2". But when you copy both "Symbol 1" and "Symbol 2" you get "Symbol 3" and "Symbol 4". We could have extra code that does a more thorough check that tries to match that "Symbol 3" is a copy of "Symbol 1" and so on, but if you rename "Symbol 1" in set ["Symbol 1", "Symbol 2"] to "Symbol 23", the next duplicated symbol name would be "Symbol 3". And if you have ["Symbol 1", "Symbol 2", "Symbol 4"], the duplicated copies will fill a spot for "Symbol 3" but skip over and become "Symbol 5" the next duplication.

With all this happening, it's better to just stick with a convention of don't name symbols with digits on the end or don't copy symbols without renaming them to something less-generic. In my code it will only get the latest copy name so looking to match an auto-named "Symbol 3" will actually find "Symbol 4" in ["Symbol 1", "Symbol 2", "Symbol 4"] but auto-named "Symbol 5" will find "Symbol 4" in ["Symbol 1", "Symbol 2", "Symbol 3",  "Symbol 4"].

#target illustrator
function test () {

	if (typeof(String.escapeForRegexp) != "function") {
		String.prototype.escapeForRegexp = function () {
			return this.replace(/([\/.*+?|()[\]{}\\^$])/g, "\\$1");
		};
	}

	if (!Array.prototype.indexOf) {
		Array.prototype.indexOf = function(searchElement, fromIndex) {
			var k;
			if (this == null) {
				throw new TypeError('"this" is null or not defined');
			}
			var o = Object(this);
			var len = o.length >>> 0;
			if (len === 0) {
				return -1;
			}
			var n = +fromIndex || 0;
			if (Math.abs(n) === Infinity) {
				n = 0;
			}
			if (n >= len) {
				return -1;
			}
			k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);
			while (k < len) {
				if (k in o && o[k] === searchElement) {
					return k;
				}
				k++;
			}
			return -1;
		};
	};

	/**
	 * Matches a name of a new copied symbol "Symbol 1" to a name in the list of symbols ["Symbol", "Other Symbol"] before processing.
	 * Will have no choice but to use latest copy name: "Symbol 3" in ["Symbol", "Symbol 1", "Symbol 2"] will result in "Symbol 2" even if the copied original was actually "Symbol 1".
	 *  {string[]} originalSymbolNames - Array of original symbol names before any were duplicated via action.
	 *  {string} symbolNameToCheck - The name of a new copied symbol.
	 *  {string} - Name of the original symbol to use, or name of the last copy of that symbol in the symbols panel.
	 */
	function getLatestSymbolCopyName (originalSymbolNames, symbolNameToCheck) {
		var thisSymbolName;
		var previousCopyNames = [];
		var endSuffixRx = /\s\d+$/;
		for (var i = 0; i < originalSymbolNames.length; i++) {
			thisSymbolName = originalSymbolNames[i];
			if (thisSymbolName.replace(endSuffixRx, "") == symbolNameToCheck.replace(endSuffixRx, "")) {
				previousCopyNames.push(thisSymbolName);
			}
		}
		previousCopyNames.sort(function (a, b) {
			if (endSuffixRx.test(a) && !endSuffixRx.test(b)) {
				return true;
			} else if (!endSuffixRx.test(a) && endSuffixRx.test(b)) {
				return false;
			}
			var aSuffix = a.match(endSuffixRx)[0].substr(1) * 1;
			var bSuffix = b.match(endSuffixRx)[0].substr(1) * 1;
			return aSuffix < bSuffix;
		});
		var latestCopyName = previousCopyNames[0];
		return latestCopyName;
	};

	/**
	 * Replaces a symbol instance art object's symbol reference to another symbol definition.
	 *  {AiSymbolItem} symbolArt - The symbol instance inside the document (on an artboard/in a layer).
	 *  {AiSymbol} symbolDefinition - Symbol definition in the Symbols panel.
	 */
	function replaceSymbolReference (symbolArt, symbolDefinition) {
		symbolArt.symbol = symbolDefinition;
	};

	function replaceDocumentArt (doc, docArt, symbolDefinition) {
		var newPlacedArt = doc.symbolItems.add(symbolDefinition);
		newPlacedArt.move(docArt, ElementPlacement.PLACEAFTER);
		newPlacedArt.height = docArt.height;
		newPlacedArt.width = docArt.width;
		newPlacedArt.top = docArt.top;
		newPlacedArt.left = docArt.left;
		docArt.remove();
		return newPlacedArt;
	};

	var doc = app.activeDocument;
	doc.layers[0].visible = true;
	doc.layers[0].locked = false;
	var sel = doc.selection;
	if (sel.length == 0) {
		alert("No selection");
		return;
	}
	var sym = doc.symbols;
	var originalSymbolNames = [];
	var endSuffixRx = /\s\d+$/;
	
	var thisSymbol, thisSymbolName;

	for (var i = 0; i < sym.length; i++) {
		thisSymbol = sym[i];
		thisSymbolName = thisSymbol.name;
		originalSymbolNames.push(thisSymbolName);
	}

	app.doScript("Duplicate Symbol", "Duplicate Symbol Set");

	var newSymbolNames = [];

	for (var i = 0; i < sym.length; i++) {
		thisSymbol = sym[i];
		thisSymbolName = thisSymbol.name;
		if (originalSymbolNames.indexOf(thisSymbolName) == -1) {
			newSymbolNames.push(thisSymbolName);
		}
	}

	if (newSymbolNames.length == 0) {
		alert("No symbols were found to be selected.");
		return;
	}

	// clean up copied symbols.
	for (var i = 0; i < newSymbolNames.length; i++) {
		thisSymbolName = newSymbolNames[i];
		thisSymbol = doc.symbols.getByName(thisSymbolName);
		thisSymbol.remove();
	}

	var selectedSymbolNames = [];
	var thisOriginalName;
	var thisNewName;
	var latestCopyName;
	for (var i = 0; i < originalSymbolNames.length; i++) {
		thisOriginalName = originalSymbolNames[i];
		for (var j = 0; j < newSymbolNames.length; j++) {
			thisNewName = newSymbolNames[j];
			if (thisNewName.replace(endSuffixRx, "") == thisOriginalName.replace(endSuffixRx, "")) {
				latestCopyName = getLatestSymbolCopyName(originalSymbolNames, thisNewName);
				selectedSymbolNames.push(latestCopyName);
				continue;
			}
		}
	}

	var symbolToPlace, symbolToPlaceName, dynamicIndex;
	var thisSelectedArt, replacingArt;
	var replacingItemUuids = [];
	for (var i = sel.length - 1; i > -1; i--) {
		thisSelectedArt = sel[i];
		dynamicIndex = Math.floor(Math.random() * selectedSymbolNames.length);
		symbolToPlaceName = selectedSymbolNames[dynamicIndex];
		symbolToPlace = sym.getByName(symbolToPlaceName);
		if (thisSelectedArt.typename == "SymbolItem") { // selected item is a symbol: replace the symbol.
			replaceSymbolReference(thisSelectedArt, symbolToPlace);
		} else if (thisSelectedArt.typename == "GroupItem" && thisSelectedArt.pageItems.length == 1) {
			if (thisSelectedArt.symbolItems.length == 1) {
				replaceSymbolReference(thisSelectedArt.symbolItems[0], symbolToPlace);
			} else {
				replacingArt = replaceDocumentArt(doc, thisSelectedArt.pageItems[0], symbolToPlace);
				replacingItemUuids.push(replacingArt.uuid);
			}
		} else {
			replacingArt = replaceDocumentArt(doc, thisSelectedArt, symbolToPlace);
			replacingItemUuids.push(replacingArt.uuid);
		}
	}

	var thisItem;
	for (var i = 0; i < replacingItemUuids.length; i++) {
		thisItem = doc.getPageItemFromUuid(replacingItemUuids[i]);
		thisItem.selected = true;
	}

};
test();

ANd here's the action file

/version 3
/name [ 20
	4475706c69636174652053796d626f6c20536574
]
/isOpen 1
/actionCount 1
/action-1 {
	/name [ 16
		4475706c69636174652053796d626f6c
	]
	/keyIndex 0
	/colorIndex 0
	/isOpen 1
	/eventCount 1
	/event-1 {
		/useRulersIn1stQuadrant 0
		/internalName (ai_plugin_symbol_palette)
		/localizedName [ 7
			53796d626f6c73
		]
		/isOpen 1
		/isOn 1
		/hasDialog 0
		/parameterCount 1
		/parameter-1 {
			/key 1835363957
			/showInPalette -1
			/type (enumerated)
			/name [ 16
				4475706c69636174652053796d626f6c
			]
			/value 4
		}
	}
}

Hi!

I need the exact action to do with a script. But it is my first time using script, how can I install it?

I tried through extendscript toolkit, but the script doesnt appear in illustrator.