How to use Save As dialog in a web page

Auto saving user input from a web page into a selected file — a use case for the modern File System Access API.

Users of some web applications want not only to see and manipulate data, they also want to export it. Before export, the users might want to customize the displayed data. For example, if the data is displayed in a table, the users might wish to filter out irrelevant rows or columns, fill some cells or adjust their values.

What to do with the exported data? Data managers or scientists, for example, use R to transform the exported data into colorful graphs with error bars. R users also prefer to see the changes reflected in their graphs as they filter the data in the web application. Could a web application keep updating the file that is used as the source data by another tool?

My message to R users is that there is no need to change the file name in the R code each time the data is exported from a web page or to delete the previously exported files in Download folder. After a user select the output file in a web page, the page output can be saved automatically to the same file either at regular intervals or in response to new input. Let’s consider how to implement a auto-save feature in a web page and, in passing, compare the few options for…