How do I update a value in a json file and save it through node.js? I have the file content:
var file_content = fs.readFileSync(filename);
var content = JSON.parse(file_content);
var val1 = content.val1;
Now I want to change the value of val1 and save it to the file.
Doing this asynchronously is quite easy. It's particularly useful if you're concerned for blocking the thread (likely).
var fs = require('fs');
var fileName = './file.json';
var file = require(fileName);
file.key = "new value";
fs.writeFile(fileName, JSON.stringify(file), function (err) {
if (err) return console.log(err);
console.log(JSON.stringify(file));
console.log('writing to ' + fileName);
});
The caveat is that json is written to the file on one line and not prettified. ex:
{
"key": "value"
}
will be...
{"key": "value"}
To avoid this, simply add these two extra arguments to JSON.stringify
JSON.stringify(file, null, 2)
null - represents the replacer function. (in this case we don't want to alter the process)
2 - represents the spaces to indent.