ee.Date.evaluate
Asynchronously retrieves the value of this object from the server and passes it to the provided callback function.
| Usage | Returns |
|---|
Date.evaluate(callback) | |
| Argument | Type | Details |
|---|
this: computedobject | ComputedObject | The ComputedObject instance. |
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. |
Examples
/**
* 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 setup
See the
Python Environment page for information on the Python API and using
geemap for interactive development.
import ee
import geemap.core as geemap
# The Earth Engine Python client library does not have an evaluate method for
# asynchronous evaluation of ee.Date objects.
# Use ee.Date.getInfo() instead.
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2023-10-06 UTC.
[null,null,["Last updated 2023-10-06 UTC."],[[["`Date.evaluate()` retrieves the value of a server-side `ee.Date` object and passes it to a callback function."],["The callback function receives the evaluated result as an object with `type` and `value` keys, where `value` represents milliseconds since the Unix epoch."],["Excessive use of `evaluate` can impact performance due to data transfer from Earth Engine servers to the client."],["The Python client library uses `getInfo()` instead of `evaluate` for asynchronous evaluation of `ee.Date` objects."]]],["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"]]