`http://localhost:8080`, y su JavaScript está tratando de comunicarse con un backend corriendo en `http://localhost` (porque no especificamos un puerto, el navegador asumirá el puerto por defecto `80`).

Entonces, el navegador enviará un request HTTP `OPTIONS` al backend `:80`, y si el backend envía los headers apropiados autorizando la comunicación desde este origen diferente (`http://localhost:8080`), entonces el navegador `:8080` permitirá que el JavaScript en el frontend envíe su request al backend...

即使它们都在 `localhost` 中，但是它们使用不同的协议或者端口，所以它们都是不同的「源」。

## 步骤

假设你的浏览器中有一个前端运行在 `http://localhost:8080`，并且它的 JavaScript 正在尝试与运行在 `http://localhost` 的后端通信（因为我们没有指定端口，浏览器会采用默认的端口 `80`）。

然后，浏览器会向后端发送一个 HTTP `OPTIONS` 请求，如果后端发送适当的 headers 来授权来自这个不同源（`http://localhost:8080`）的通信，浏览器将允许前端的 JavaScript 向后端发送请求。

为此，后端必须有一个「允许的源」列表。

在这种情况下，它必须包含 `http://localhost:8080`，前端才能正常工作。

## 通配符

也可以使用 `"*"`（一个「通配符」）声明这个列表，表示全部都是允许的。

        addErrorProneDependency("com.uber.nullaway:nullaway:0.12.10")

        project.tasks.named<JavaCompile>(this.compileJavaTaskName) {
            options.errorprone {
                isEnabled = extension.enabled
                checks = errorproneExtension.disabledChecks.map {
                    it.associateWith { CheckSeverity.OFF }
                }

		Versioned:  globalBucketVersioningSys.PrefixEnabled(oi.Bucket, oi.Name),
		Expiration: ExpirationOptions{Expire: true},
	}
	if lcEvent.Action.DeleteVersioned() {
		opts.VersionID = oi.VersionID
	}
	tags := newLifecycleAuditEvent(src, lcEvent).Tags()
	if lcEvent.Action.DeleteRestored() {
		// delete locally restored copy of object or object version
		// from the source, while leaving metadata behind. The data on

		c.Fatalf("bucket creat error: %v", err)
	}

	// Create a policy policy
	policy := "mypolicy"
	policyBytes := fmt.Appendf(nil, `{
 "Version": "2012-10-17",
 "Statement": [
  {
   "Effect": "Allow",
   "Action": [
    "s3:PutObject",
    "s3:GetObject",
    "s3:ListBucket"
   ],
   "Resource": [
    "arn:aws:s3:::%s/*"
   ]
  }
 ]
}`, bucket)
	err = s.adm.AddCannedPolicy(ctx, policy, policyBytes)

All these parameters can be different than "`static`", adjust them with the needs and specific details of your own application.

## More info { #more-info }

    includeSpockAnnotation("org.gradle.integtests.fixtures.compatibility.MultiVersionTestCategory")
    (options as JUnitPlatformOptions).includeEngines("spock")
    failOnNoDiscoveredTests.set(false)
    setSystemPropertiesOfTestJVM("all")

	o.Lifecycle = lc
	o.Versioning = vc
	o.Replication = replicationConfig{
		Config:  replCfg,
		remotes: tgts,
	}
	o.Retention = rcfg
}

// newMetacache constructs a new metacache from the options.
func (o listPathOptions) newMetacache() metacache {
	return metacache{
		id:          o.ID,
		bucket:      o.Bucket,
		root:        o.BaseDir,
		recursive:   o.Recursive,
		status:      scanStateStarted,

        If you found a clear typo, please open a PR with a fix instead of opening an issue.

  - type: dropdown
    id: issue-type
    attributes:
      label: Issue type
      options:
        - Wrong or misleading information
        - Missing information
        - Styling or Accessibility
        - Typo (please open a PR instead)
    validations:
      required: true
  - type: textarea

- TensorFlow library (version, if pip package or github SHA, if built from source):

### 2. Code

Provide code to help us reproduce your issues using one of the following options:

#### Option A: Reference colab notebooks