If a promise reaches fulfilled or rejected state, it is resolved. 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.

So if you don’t need the old URL anymore, you should call the revokeObjectURL() API to free them.) Code language: JavaScript ( javascript )

For example, if we name the file as *.csv and give it type: 'text/csv', Firefox will recognize it as “CSV document” and suggest you open it with LibreOffice Calc.Īnd in the last line we assign the url to the element’s href attribute, so when the user clicks on the link, the browser will initiate an download action (or other default action for the specific file type.)Įverytime you call createObjectURL(), a new object URL will be created, which will use up the memory if you call it many times. Other commonly seen formats include application/json and text/csv. If you assign the correct format, the browser can better handle the file. Notice that you can assign the type of the data in the new Blob() constructor. The URL lives as long as the document in the window on which it was created. EDIT 20220721 4 using a mix of named approaches: Open a new tab for the downloads (as Browser will use dedicated memory for this), but execute all downloads sequentially after each other. The magic happens on the third line, the () API takes a Blob and returns an URL to access it. Var url = (data) ĭocument.getElementById('download_link').href = url

Javascript download function