Node.js fsPromises.writeFile()方法
原文:https://www . geesforgeks . org/node-js-fspromiss-write file-method/
fsPromises.writeFile() 方法用于将指定的数据异步写入文件。默认情况下，如果文件存在，它将被替换。“选项”参数可用于修改方法的功能。
成功之后，承诺将会毫无争议地实现。
语法:
fsPromises.writeFile( file, data, options )
参数:该方法接受三个参数，如上所述，如下所述:
- File: It is a string, Buffer, URL or file description integer, indicating the file path that must be written. Using the file descriptor will make it behave like the fsPromises.write () method.
- Data: is the string, Buffer, TypedArray or DataView to be written into the file.
- Option: is a string or object that can be used to specify optional parameters that affect output. It has three optional parameters:
- Code: is a string value that specifies the file code. The default value is utf8.
- Mode: An integer value that specifies the file mode. The default value is 0o666.
- Flag: It is a string value that specifies the flag used when writing to the file. The default value is "w".
返回值:该方法返回一个承诺。
下面的例子说明了 Node.js 中的方法:
例 1:
// Node.js program to demonstrate the
// fsPromises.writeFile() method
// Import the filesystem module
const fs = require('fs');
const fsPromises = require('fs').promises;
let data = "This is a file containing"
+ " a collection of movies.";
(async function main() {
try {
await fsPromises.writeFile(
"movies.txt", data)
console.log("File written successfully");
console.log("The written file has"
+ " the following contents:");
console.log("" +
fs.readFileSync("./movies.txt"));
} catch (err) {
console.error(err);
}
})();
输出:
File written successfully
The written file has the following contents:
This is a file containing a collection of movies.
例 2:
// Node.js program to demonstrate the
// fsPromises.writeFile() method
// Import the filesystem module
const fs = require('fs');
const fsPromises = require('fs').promises;
let data = "This is a file containing"
+ " a collection of books.";
(async function main() {
try {
await fsPromises.writeFile(
"books.txt", data, {
encoding: "utf8",
flag: "w",
mode: 0o666
});
console.log("File written successfully\n");
console.log("The written has the "
+ "following contents:");
console.log("" +
fs.readFileSync("books.txt"));
}
catch (err) {
console.error(err);
}
})();
输出:
File written successfully
The written has the following contents:
This is a file containing a collection of books.
参考:T2【https://nodejs . org/API/fs . html # fs _ fspromises _ write file _ file _ data _ options
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