在 AWS JavaScript SDK v3 中，可以使用 S3Client 的 'putObject” 方法来完成 S3 ManagedUpload 相关的操作。

以下是示例代码：

const { S3Client, PutObjectCommand } = require("@aws-sdk/client-s3");
const fs = require('fs');

async function uploadFileToS3() {
  // Create S3 Client object
  const s3 = new S3Client({ region: "us-west-2" });

  // Set S3 bucket name and key
  const bucketName = "myBucket";
  const keyName = "myFile.txt";

  // Read file content
  const fileContent = fs.readFileSync("path/to/file.txt");

  // Create PutObjectCommand with file content and required parameters
  const command = new PutObjectCommand({
    Bucket: bucketName,
    Key: keyName,
    Body: fileContent,
  });

  try {
    // Execute PutObjectCommand to upload file to S3
    const response = await s3.send(command);
    console.log("File uploaded successfully! Object URL: " + response.Location);
  } catch (err) {
    console.log("Error uploading file:", err);
  }
}

uploadFileToS3();

注意，此示例代码仅上传文件，但适用于任何 S3 ManagedUpload 操作。如果要使用其他选项（例如，设置 ACL、Content-Type 等），可以在 PutObjectCommand 中添加相应的属性。请参阅 AWS JavaScript SDK v3 的文档以获取更多信息。