The following simple function allow you to generate a download of a file directly in the browser without contact any server. In this article we are going to show you a couple of tricks to generate and download directly a file using pure Javascript. Therefore, the automatic download of file has been difficult to achieve in the latest years, but now with the introduction of HTML5, this task has become easier to achieve. However, in the latest browsers unknow or rare downloaded file extensions are blocked and a prompt appears if you really want to open that file (at less in Chrome). Then inside the onload event handler, the received Byte Array (Binary. Inside the DownloadFile JavaScript function, the URL of the File is passed as parameter to the GET call of the JavaScript XmlHttpRequest call. When the Download Button is clicked, the DownloadFile JavaScript function is called. Imagine that you use Google Chrome and you have enabled the option 'Auto-open downloaded files', and for your bad luck you enter in a malicious website and it generates the download of an unknown file. Downloading Excel File using AJAX in JavaScript. If a promise reaches fulfilled or rejected state, it is resolved.Generate and download a file using Javascript ? If you think about it, this isn't so secure as you think and shouldn't be allowed without the user interaction (however now is allowed). Once a new Promise object is created, its state is pending. Also, it cannot go back from the fulfilled or rejected state to the pending state. In other words, a promise cannot go from the fulfilled state to the rejected state and vice versa. Once a promise reaches either fulfilled or rejected state, it stays in that state and can’t go to another state. In case of an error, the executor will call the reject() function to change the state of the promise from pending to rejected with the error reason. If the asynchronous operation completes successfully, the executor will call the resolve() function to change the state of the promise from pending to fulfilled with a value. Note that the callback functions passed into the executor are resolve and reject by convention only. In turn, the executor accepts two callback functions with the name resolve and reject. This function is often referred to as an executor. The promise constructor accepts a callback function that typically performs an asynchronous operation. ) Code language: JavaScript ( javascript )

Javascript download function