Writing into a file in javascript

The last one is Callback function which has two more parameters error, txtString. If at any instance it fails to load or read the file then it returns error or exception otherwise it returns all data of the file. Another method is by using a web page ActiveX objects but this method is mainly work in Internet Explorer only. This ActiveXObject is used to return an instance of a file system library which is used with the CreateTextFile method.

This JS method which generates a file defined functions and states a TextStream object to read from or write to the file. It also returns a boolean value on the basis of this we can find out that we can overwrite to the current file or not. So, if you want to add the data to the created file you can use writeline method which is used to add text string to the file. The ActiveX object contains three things libraryname, classname, location. So, classname is the instance of a class that needs to be created.

Another approach is by using php. In this, we use some inbuilt javascript functions for reading and writing data to the files. These are some functions fopen , fread and fwrite that we use here.

The function readFile is used when we want to read the content of some file. The readFile function is used for reading operations; it also accepts three parameters as mentioned above. Suppose we are and the program is in the same file then we have to just specify the file name and not the path we want to read.

The default buffer is used, If no argument is passed. Callback Function : It is the function that further has two different arguments. These arguments are err and data. If the operation is not successful in extracting the data from the file then the err shows what the fault is, else if the operation is successful then the data argument has the data from the file. Then, we will access the readFile function, provide it the file name you want to read data from, and write a callback function for error handling and showing data:.

After completing the code for reading the data from the file, the whole code snippet will look exactly like this:. Once all the code is written and when you will execute the above-given code, it will read the desired file from the browser and show all the data on the console, as shown in the screenshot given below:.

We then use file systems to read or write data to a file. In this article, we saw how to read or write text into a file in JavaScript. Easy Normal Medium Hard Expert. Writing code in comment? Please use ide. Load Comments. What's New. Most popular in JavaScript. Most visited in Web Technologies. Installation of Node. Web 1. We use cookies to ensure you have the best browsing experience on our website.

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