公告：凡是在
2025 年 4 月 15 日前註冊使用 Earth Engine 的非商業專案，都必須
驗證非商業用途資格，才能繼續存取 Earth Engine。
ee.Date.evaluate
透過集合功能整理內容
你可以依據偏好儲存及分類內容。
從伺服器非同步擷取這個物件的值，並傳遞至提供的回呼函式。
| 用量 | 傳回 |
|---|
Date.evaluate(callback) | |
| 引數 | 類型 | 詳細資料 |
|---|
這個：computedobject | ComputedObject | ComputedObject 例項。 |
callback | 函式 | 伺服器傳回答案時呼叫的函式，格式為 function(success, failure)。如果要求成功，success 引數會包含評估結果。如果要求失敗，失敗引數會包含錯誤訊息。 |
範例
程式碼編輯器 (JavaScript)
/**
* WARNING: this function transfers data from Earth Engine servers to the
* client. Doing so can negatively affect request processing and client
* performance. Server-side options should be used whenever possible.
* Learn more about the distinction between server and client:
* https://developers.google.com/earth-engine/guides/client_server
*/
// A server-side ee.Date object.
var dateServer = ee.Date('2021-4-30');
// Use evaluate to transfer server-side date to the client. The result is
// an object with keys "type" and "value" where "value" is milliseconds since
// Unix epoch.
dateServer.evaluate(function(dateClient) {
print('Client-side date is an object', typeof dateClient);
print('Object keys include "type" and "value"', Object.keys(dateClient));
print('"value" is milliseconds since Unix epoch', dateClient.value);
print('Client-side date in JS Date constructor', new Date(dateClient.value));
});
Python 設定
請參閱
Python 環境頁面，瞭解 Python API 和如何使用 geemap 進行互動式開發。
import ee
import geemap.core as geemap
Colab (Python)
# The Earth Engine Python client library does not have an evaluate method for
# asynchronous evaluation of ee.Date objects.
# Use ee.Date.getInfo() instead.
除非另有註明，否則本頁面中的內容是採用創用 CC 姓名標示 4.0 授權，程式碼範例則為阿帕契 2.0 授權。詳情請參閱《Google Developers 網站政策》。Java 是 Oracle 和/或其關聯企業的註冊商標。
上次更新時間：2025-07-26 (世界標準時間)。
[null,null,["上次更新時間：2025-07-26 (世界標準時間)。"],[[["\u003cp\u003e\u003ccode\u003eDate.evaluate()\u003c/code\u003e retrieves the value of a server-side \u003ccode\u003eee.Date\u003c/code\u003e object and passes it to a callback function.\u003c/p\u003e\n"],["\u003cp\u003eThe callback function receives the evaluated result as an object with \u003ccode\u003etype\u003c/code\u003e and \u003ccode\u003evalue\u003c/code\u003e keys, where \u003ccode\u003evalue\u003c/code\u003e represents milliseconds since the Unix epoch.\u003c/p\u003e\n"],["\u003cp\u003eExcessive use of \u003ccode\u003eevaluate\u003c/code\u003e can impact performance due to data transfer from Earth Engine servers to the client.\u003c/p\u003e\n"],["\u003cp\u003eThe Python client library uses \u003ccode\u003egetInfo()\u003c/code\u003e instead of \u003ccode\u003eevaluate\u003c/code\u003e for asynchronous evaluation of \u003ccode\u003eee.Date\u003c/code\u003e objects.\u003c/p\u003e\n"]]],["The `Date.evaluate(callback)` method asynchronously retrieves a ComputedObject's value from the server. It uses a callback function with `success` and `failure` arguments to handle the server's response. If successful, `success` provides the evaluated result; otherwise, `failure` gives an error message. The JavaScript example transfers a server-side date to the client, revealing its \"type\" and \"value\" (milliseconds since Unix epoch). Python uses `ee.Date.getInfo()` for similar functionality.\n"],null,["# ee.Date.evaluate\n\n\u003cbr /\u003e\n\nAsynchronously retrieves the value of this object from the server and passes it to the provided callback function.\n\n\u003cbr /\u003e\n\n| Usage | Returns |\n|---------------------------|---------|\n| Date.evaluate`(callback)` | |\n\n| Argument | Type | Details |\n|------------------------|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| this: `computedobject` | ComputedObject | The ComputedObject instance. |\n| `callback` | Function | A function of the form function(success, failure), called when the server returns an answer. If the request succeeded, the success argument contains the evaluated result. If the request failed, the failure argument will contains an error message. |\n\nExamples\n--------\n\n### Code Editor (JavaScript)\n\n```javascript\n/**\n * WARNING: this function transfers data from Earth Engine servers to the\n * client. Doing so can negatively affect request processing and client\n * performance. Server-side options should be used whenever possible.\n * Learn more about the distinction between server and client:\n * https://developers.google.com/earth-engine/guides/client_server\n */\n\n// A server-side ee.Date object.\nvar dateServer = ee.Date('2021-4-30');\n\n// Use evaluate to transfer server-side date to the client. The result is\n// an object with keys \"type\" and \"value\" where \"value\" is milliseconds since\n// Unix epoch.\ndateServer.evaluate(function(dateClient) {\n print('Client-side date is an object', typeof dateClient);\n print('Object keys include \"type\" and \"value\"', Object.keys(dateClient));\n print('\"value\" is milliseconds since Unix epoch', dateClient.value);\n print('Client-side date in JS Date constructor', new Date(dateClient.value));\n});\n```\nPython setup\n\nSee the [Python Environment](/earth-engine/guides/python_install) page for information on the Python API and using\n`geemap` for interactive development. \n\n```python\nimport ee\nimport geemap.core as geemap\n```\n\n### Colab (Python)\n\n```python\n# The Earth Engine Python client library does not have an evaluate method for\n# asynchronous evaluation of ee.Date objects.\n# Use ee.Date.getInfo() instead.\n```"]]
