predictit.js

// Function to calculate the return from betting "No" on all reasonable markets in a PredictIt.com Linked market type.
// Execute by browsing to the linked market overview, and pasting function into the Developer Console window (F12)
//
// 	The formula is as follows:
//	Add up all the No's that will give profit (and adjust for predict it tax) NOTE: Do not count the answer that is a yes. 
//	This answer is a loss and is subtracted from the rest.
//
//	Example: 	Rubio_No:47¢	Cruz_No:59¢		Kasich_No:94¢	Bush_No:95¢
//	
// 	We buy 1 share of each. Now let's see how a Rubio_Yes would play out.
//	Well we lose our 47¢ we bought his 'No' share for.
// 	Next, we add up all the profits WITH Predictit Tax deducted BUT we DON'T count Rubio, cause he won. 41(.9)+6(.9)+5(.9) = 46.8 respectively.
//	Subtract our loss against it 46.8 (profit) - 47 = -.2 loss	
//
// 	Let's see how a Cruz_Yes would play out
//	Well we lose our 59¢ we bought his 'No' share for.
// 	Next, we add up all the profits WITH Predictit Tax deducted BUT we DON'T count Cruz, cause he won. 53(.9)+6(.9)+5(.9) = 57.6 respectively.
//	Subtract our loss against it 57.6 (profit) - 59 = -1.4 loss	
//
//	Ok, so the formula, we want to go through each answer and add up all the No's that would give us money and subtract the No loss share. 
//	This is done looping through an our array of answers (in this case people) and an array within that. see below

(function () {
	
	// Get the prices of each "No" option.
	var noList = $('#contractListTable .sharesDown > .sharesDown').text().split('¢').filter(function (item) {
			// Filter out options not currently traded, or costing more than $0.96.
			return !(item === '' || item.indexOf('None') > -1 || item >= 97); 
		}).map(function (item, idx) {
			return parseInt(item) / 100;
		});

	
	// var totalCost = noList.reduce((a, b) => a + b, 0);
	// var returns = noList.length -1;
	
	// var totalProfit = returns - totalCost;
	// var adjustedProfit = totalProfit * (totalProfit > 0 ? 0.9 : 1); // Adjusted after fees
	// var ror = adjustedProfit / totalCost;
	
	console.clear();

	var highestPotentialPercent;
	var lowestPotentialPercent;

//Go through the answers
	for (i = 0; i < noList.length; i++) { 
	    //console.log("Person " + (i+1) + ":" + noList[i]);

	    var adjustedTotal = 0;

	    //If there's a match, we want to ignore it (we're representing the answer that got a 'Yes')
	    //all that's left are the totals 
	    for (j = 0; j < noList.length; j++) {
	    	if(i!=j)
	    	{
	    		//add up adjusted total (how much we'd win, profit only)
	    		adjustedTotal += (1-noList[j])*.9;
	    	}	    	
	    }
	    var percentGainOrLoss = ((adjustedTotal - noList[i])*100).toFixed(1);
		//subtract total against the money we lost (whoever got the Yes which is 'i')
	    //console.log("Person " + (i+1) + ":" + percentGainOrLoss + "%");

	    if(highestPotentialPercent == null){
	    	highestPotentialPercent = percentGainOrLoss;
	    }else{
	    	if(highestPotentialPercent > percentGainOrLoss)
	    		highestPotentialPercent = percentGainOrLoss;
	    }

	    if(lowestPotentialPercent == null){
	    	lowestPotentialPercent = percentGainOrLoss;
	    }else{
	    	if(lowestPotentialPercent < percentGainOrLoss)
	    		lowestPotentialPercent = percentGainOrLoss;
	    }
	}
	if(lowestPotentialPercent > 0){
		console.log('---GOOD BET---');
		console.log('Lowest Potential Gain:' + lowestPotentialPercent + '%');
		console.log('Highest Potential Gain:' + highestPotentialPercent + '%');
	}else{
		if(highestPotentialPercent < 0)
		{
			console.log('---BAD BET---');
			console.log('Lowest Potential Loss:' + lowestPotentialPercent + '%');
			console.log('Highest Potential Loss:' + highestPotentialPercent + '%');
		}else{
			console.log('---OK BET---');
			console.log('Lowest Potential Loss:' + lowestPotentialPercent + '%');
			console.log('Highest Potential Gain:' + highestPotentialPercent + '%');
		}
	}

	//console.log('Total Profit: $' + totalProfit.toFixed(2));
	//console.log('Total Cost: $' + totalCost.toFixed(2));
	//console.log('Net Profit: $' + adjustedProfit.toFixed(2));
	//console.log('Rate of Return: ' + ror.toFixed(2) + '%');
	
	// If the move is profitable, calculate how much investment would yield a easily measured return.
	//if (adjustedProfit > 0) {
	//	console.log('It would cost $' + (10 / ror).toFixed(2) + ' to earn $10');
	//}
})();