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Save-Data header field is a boolean which, in requests, indicates the client's preference for reduced data usage. This could be for reasons such as high transfer costs, slow connection speeds, etc.

A value of On indicates explicit user opt-in into a reduced data usage mode on the client, and when communicated to origins allows them to deliver alternative content to reduce the data downloaded such as smaller image and video resources, different markup and styling, disabled polling and automatic updates, and so on.

注意 : Disabling HTTP/2 Server Push ( RFC 7540, section 8.2: Server Push ) might be desirable too for reducing data downloads.

句法 

Save-Data: <sd-token>

指令

<sd-token>
A numerical value indicating whether the client wants to opt in to reduced data usage mode. on indicates yes, while off (the default) indicates no.

范例

Vary header ensures that the content is cached properly (for instance ensuring that the user is not served a lower-quality image from the cache when Save-Data header is no longer present [ e.g. after having switched from cellular to Wi-Fi]).

With Save-Data: on

Request: 

GET /image.jpg HTTP/1.0
Host: example.com
Save-Data: on

Response: 

HTTP/1.0 200 OK
Content-Length: 102832
Vary: Accept-Encoding, Save-Data
Cache-Control: public, max-age=31536000
Content-Type: image/jpeg
[...]

Without Save-Data

Request: 

GET /image.jpg HTTP/1.0
Host: example.com

Response: 

HTTP/1.0 200 OK
Content-Length: 481770
Vary: Accept-Encoding, Save-Data
Cache-Control: public, max-age=31536000
Content-Type: image/jpeg
[...]

规范

规范 Title
draft-grigorik-http-client-hints-03, section 7: Save-Data HTTP Client Hints

浏览器兼容性

更新 GitHub 上的兼容性数据
Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Save-Data Experimental Chrome 完整支持 49 Edge 完整支持 ≤79 Firefox ? IE ? Opera 完整支持 35 Safari ? WebView Android 完整支持 49 Chrome Android 完整支持 49 Firefox Android ? Opera Android 完整支持 35 Safari iOS ? Samsung Internet Android 完整支持 5.0

图例

完整支持

完整支持

兼容性未知 ?

兼容性未知

实验。期望将来行为有所改变。

实验。期望将来行为有所改变。

另请参阅

元数据

  • 最后修改：
  1. HTTP
  2. Guides:
  3. Resources and URIs
    1. Identifying resources on the Web
    2. Data URIs
    3. Introduction to MIME Types
    4. Complete list of MIME Types
    5. Choosing between www and non-www URLs
  4. HTTP guide
    1. Basics of HTTP
    2. HTTP 概述
    3. Evolution of HTTP
    4. HTTP Messages
    5. A typical HTTP session
    6. Connection management in HTTP/1.x
    7. Protocol upgrade mechanism
  5. HTTP 安全性
    1. Content Security Policy (CSP)
    2. HTTP Public Key Pinning (HPKP)
    3. HTTP Strict Transport Security (HSTS)
    4. Cookie security
    5. X-Content-Type-Options
    6. X-Frame-Options
    7. X-XSS-Protection
    8. Mozilla web security guidelines
    9. Mozilla Observatory
  6. HTTP access control (CORS)
  7. HTTP authentication
  8. HTTP caching
  9. HTTP compression
  10. HTTP conditional requests
  11. HTTP content negotiation
  12. HTTP cookies
  13. HTTP range requests
  14. HTTP redirects
  15. HTTP specifications
  16. Feature policy
  17. 参考：
  18. HTTP 头
    1. Accept
    2. Accept-CH
    3. Accept-CH-Lifetime
    4. Accept-Charset
    5. Accept-Encoding
    6. Accept-Language
    7. Accept-Patch
    8. Accept-Ranges
    9. Access-Control-Allow-Credentials
    10. Access-Control-Allow-Headers
    11. Access-Control-Allow-Methods
    12. Access-Control-Allow-Origin
    13. Access-Control-Expose-Headers
    14. Access-Control-Max-Age
    15. Access-Control-Request-Headers
    16. Access-Control-Request-Method
    17. Age
    18. Allow
    19. Alt-Svc
    20. Authorization
    21. Cache-Control
    22. Clear-Site-Data
    23. Connection
    24. Content-Disposition
    25. Content-Encoding
    26. Content-Language
    27. Content-Length
    28. Content-Location
    29. Content-Range
    30. Content-Security-Policy
    31. Content-Security-Policy-Report-Only
    32. Content-Type
    33. Cookie
    34. Cookie2
    35. Cross-Origin-Embedder-Policy
    36. Cross-Origin-Opener-Policy
    37. Cross-Origin-Resource-Policy
    38. DNT
    39. DPR
    40. Date
    41. Device-Memory
    42. Digest
    43. ETag
    44. Early-Data
    45. Expect
    46. Expect-CT
    47. Expires
    48. Feature-Policy
    49. Forwarded
    50. From
    51. Host
    52. If-Match
    53. If-Modified-Since
    54. If-None-Match
    55. If-Range
    56. If-Unmodified-Since
    57. 索引
    58. Keep-Alive
    59. Large-Allocation
    60. Last-Modified
    61. Link
    62. Location
    63. NEL
    64. Origin
    65. Pragma
    66. Proxy-Authenticate
    67. Proxy-Authorization
    68. Public-Key-Pins
    69. Public-Key-Pins-Report-Only
    70. Range
    71. Referer
    72. Referrer-Policy
    73. Retry-After
    74. Save-Data
    75. Sec-Fetch-Dest
    76. Sec-Fetch-Mode
    77. Sec-Fetch-Site
    78. Sec-Fetch-User
    79. Sec-WebSocket-Accept
    80. Server
    81. Server-Timing
    82. Set-Cookie
    83. Set-Cookie2
    84. SourceMap
    85. Strict-Transport-Security
    86. TE
    87. Timing-Allow-Origin
    88. Tk
    89. Trailer
    90. Transfer-Encoding
    91. Upgrade-Insecure-Requests
    92. User-Agent
    93. Vary
    94. Via
    95. WWW-Authenticate
    96. Want-Digest
    97. 警告
    98. X-Content-Type-Options
    99. X-DNS-Prefetch-Control
    100. X-Forwarded-For
    101. X-Forwarded-Host
    102. X-Forwarded-Proto
    103. X-Frame-Options
    104. X-XSS-Protection
  19. HTTP 请求方法
    1. CONNECT
    2. DELETE
    3. GET
    4. HEAD
    5. OPTIONS
    6. PATCH
    7. POST
    8. PUT
    9. TRACE
  20. HTTP 响应状态码
    1. 100 Continue
    2. 101 Switching Protocols
    3. 103 Early Hints
    4. 200 OK
    5. 201 Created
    6. 202 Accepted
    7. 203 Non-Authoritative Information
    8. 204 No Content
    9. 205 Reset Content
    10. 206 Partial Content
    11. 300 Multiple Choices
    12. 301 Moved Permanently
    13. 302 Found
    14. 303 See Other
    15. 304 Not Modified
    16. 307 Temporary Redirect
    17. 308 Permanent Redirect
    18. 400 Bad Request
    19. 401 Unauthorized
    20. 402 Payment Required
    21. 403 Forbidden
    22. 404 Not Found
    23. 405 Method Not Allowed
    24. 406 Not Acceptable
    25. 407 Proxy Authentication Required
    26. 408 Request Timeout
    27. 409 Conflict
    28. 410 Gone
    29. 411 Length Required
    30. 412 Precondition Failed
    31. 413 Payload Too Large
    32. 414 URI Too Long
    33. 415 Unsupported Media Type
    34. 416 Range Not Satisfiable
    35. 417 Expectation Failed
    36. 418 I'm a teapot
    37. 422 Unprocessable Entity
    38. 425 Too Early
    39. 426 Upgrade Required
    40. 428 Precondition Required
    41. 429 Too Many Requests
    42. 431 Request Header Fields Too Large
    43. 451 Unavailable For Legal Reasons
    44. 500 Internal Server Error
    45. 501 Not Implemented
    46. 502 Bad Gateway
    47. 503 Service Unavailable
    48. 504 Gateway Timeout
    49. 505 HTTP Version Not Supported
    50. 506 Variant Also Negotiates
    51. 507 Insufficient Storage
    52. 508 Loop Detected
    53. 510 Not Extended
    54. 511 Network Authentication Required
  21. CSP directives
    1. CSP: base-uri
    2. CSP: block-all-mixed-content
    3. CSP: child-src
    4. CSP: connect-src
    5. CSP: default-src
    6. CSP: font-src
    7. CSP: form-action
    8. CSP: frame-ancestors
    9. CSP: frame-src
    10. CSP: img-src
    11. CSP: manifest-src
    12. CSP: media-src
    13. CSP: navigate-to
    14. CSP: object-src
    15. CSP: plugin-types
    16. CSP: prefetch-src
    17. CSP: referrer
    18. CSP: report-to
    19. CSP: report-uri
    20. CSP: require-sri-for
    21. CSP: sandbox
    22. CSP: script-src
    23. CSP: script-src-attr
    24. CSP: script-src-elem
    25. CSP: style-src
    26. CSP: style-src-attr
    27. CSP: style-src-elem
    28. CSP: trusted-types
    29. CSP: upgrade-insecure-requests
    30. CSP: worker-src
  22. CORS errors
    1. Reason: CORS disabled
    2. Reason: CORS header 'Access-Control-Allow-Origin' does not match 'xyz'
    3. Reason: CORS header 'Access-Control-Allow-Origin' missing
    4. Reason: CORS header ‘Origin’ cannot be added
    5. Reason: CORS preflight channel did not succeed
    6. Reason: CORS request did not succeed
    7. Reason: CORS request external redirect not allowed
    8. Reason: CORS request not HTTP
    9. Reason: Credential is not supported if the CORS header ‘Access-Control-Allow-Origin’ is ‘*’
    10. Reason: Did not find method in CORS header ‘Access-Control-Allow-Methods’
    11. Reason: Multiple CORS header 'Access-Control-Allow-Origin' not allowed
    12. Reason: expected ‘true’ in CORS header ‘Access-Control-Allow-Credentials’
    13. Reason: invalid token ‘xyz’ in CORS header ‘Access-Control-Allow-Headers’
    14. Reason: invalid token ‘xyz’ in CORS header ‘Access-Control-Allow-Methods’
    15. Reason: missing token ‘xyz’ in CORS header ‘Access-Control-Allow-Headers’ from CORS preflight channel
  23. Feature-Policy directives
    1. Feature-Policy: accelerometer
    2. Feature-Policy: ambient-light-sensor
    3. Feature-Policy: autoplay
    4. Feature-Policy: battery
    5. Feature-Policy: camera
    6. Feature-Policy: display-capture
    7. Feature-Policy: document-domain
    8. Feature-Policy: encrypted-media
    9. Feature-Policy: fullscreen
    10. Feature-Policy: geolocation
    11. Feature-Policy: gyroscope
    12. Feature-Policy: layout-animations
    13. Feature-Policy: legacy-image-formats
    14. Feature-Policy: magnetometer
    15. Feature-Policy: microphone
    16. Feature-Policy: midi
    17. Feature-Policy: oversized-images
    18. Feature-Policy: payment
    19. Feature-Policy: picture-in-picture
    20. Feature-Policy: publickey-credentials-get
    21. Feature-Policy: screen-wake-lock
    22. Feature-Policy: sync-xhr
    23. Feature-Policy: unoptimized-images
    24. Feature-Policy: unsized-media
    25. Feature-Policy: usb
    26. Feature-Policy: vibrate
    27. Feature-Policy: vr
    28. Feature-Policy: wake-lock
    29. Feature-Policy: xr
    30. Feature-Policy: xr-spatial-tracking
    31. web-share