Exemple of call to Portfolio Optimizer API, to comput (arithmetic) assets returns from assets prices, directly from a webpage

arithmetic_returns_from_webpage.js

function arithmeticReturns(assetsPrices) {
    var xhr = new XMLHttpRequest();
    var url = "https://api.portfoliooptimizer.io/v1/assets/returns"; 
    xhr.open("POST", url, true);
    xhr.setRequestHeader("Content-Type", "application/json");
    xhr.onreadystatechange = function () {
        if (this.readyState === XMLHttpRequest.DONE) {
            // Status 200 == all good
            if (this.status === 200) { 
                // Parse the response as JSON
                var json = JSON.parse(xhr.responseText);	
        
                // Decode the assets returns, c.f. the documentation
                // at https://docs.portfoliooptimizer.io/
                var assets = json.assets;
			
                // Do whatever is needed with the assets returns
                //
            }
            // Status 429 == there are too many requests in parallel
            //
            // Waiting 1s before sending the same XHR query again is required with 
            // the free usage of Portfolio Optimizer
            else if (this.status === 429) { 
                setTimeout(function(){ arithmeticReturns(assetsPrices) }, 1000); ;
            }
        }
    };
    var data = JSON.stringify({"assets": assetsPrices.length, 
                               "assetsPrices":assetsPrices});
    xhr.send(data);
}