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Cloud Object Storage

DokumentasiCloud Object StorageSDK DocumentationNode.js SDKObject OperationsHEAD Object

HEAD Object

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Terakhir diperbarui: 2025-12-22 17:28:14

Introduction

This document describes the sample code and description for querying object metadata via the Node.js SDK in COS.

Notes

If you want to query the metadata of the target object, you need to have read permission for the target object: when you configure the authorization policy, the action needs to be set to cos:HeadObject. For more authorization, see business interfaces supporting CAM.

Feature Overview

Query the metadata information of an object.

Preliminary Preparation

Before starting to use, ensure that you have completed SDK initialization.

Use Case

cos.headObject({
    Bucket: 'examplebucket-1250000000', // Fill in your own bucket; mandatory field.
    Region: 'COS_REGION',  // Bucket region, for example ap-beijing; mandatory field.
    Key: '1.jpg',  // object key stored in the bucket (for example, 1.jpg, a/b/test.txt); mandatory field.
}, function(err, data) {
    console.log(err || data);
});

Parameter Description

Parameter Name
Parameter Description
Type
Required
Bucket
The name of the bucket, in the format of BucketName-APPID; the bucket name filled in here must be in this format.
String
Yes
Region
Bucket region; for enumerated values, see Regions and Access Domains
String
Yes
Key
Object key (name of the Object), which uniquely identifies the object in the bucket. For details, see Object Overview
String
Yes
IfModifiedSince
If the object has been modified after the specified time, the metadata information of the corresponding object is returned; otherwise, 304 is returned.
String
No

Description of the callback function

function(err, data) { ... }
Parameter Name
Parameter Description
Type
err
The object returned when an error occurs in the request, including network errors and business errors. It is null if the request is successful. For more details, see Error Codes.
Object
- statusCode
HTTP status code returned by the request, such as 200, 403, 404.
Number
- headers
Header returned by the request
Object
data
The object returned when the request is successful, or null if an error occurs in the request.
Object
- ETag
The unique identifier of the returned file. For files uploaded via simple upload, the ETag is the MD5 hash of the file. The value of the ETag can be used to check whether the object was corrupted during the upload process.
For example, "09cba091df696af91549de27b8e7d0f6", Note: The ETag value string is enclosed in double quotes.
String
- VersionId
When an object is uploaded to a bucket with versioning enabled, the version ID of the object is returned; if versioning has never been enabled for the bucket, this parameter is not returned.
String
- statusCode
HTTP status code returned by the request, such as 200, 304, and so on. It returns 304 if the resource has not been modified after the specified time.
Number
- headers
Header returned by the request
Object
- - x-cos-object-type
Indicates whether the object can be appended to. Enumerated values: normal, appendable. By default, normal is not returned.
String
- - x-cos-storage-class
The storage class of the object. Enumerated values: STANDARD, STANDARD_IA, ARCHIVE, DEEP_ARCHIVE, and so on. Default: STANDARD (not returned). For more storage classes, see Storage Class Overview.
String
- - x-cos-meta-*
User-defined metadata
String
- - NotModified
Whether the object has not been modified after the specified time
Boolean

API Operations

Description of the API interface for querying object metadata, see the HEAD Object document.
Topik sebelumnya: Restoring Archived ObjectsTopik selanjutnya: Checking Whether an Object Exists

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