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// Copyright 2020 New Relic Corporation. All rights reserved.
// SPDX-License-Identifier: Apache-2.0
package newrelic
import (
"encoding/json"
)
var (
browserStartTag = []byte(`<script type="text/javascript">`)
browserEndTag = []byte(`</script>`)
browserInfoPrefix = []byte(`window.NREUM||(NREUM={});NREUM.info=`)
)
// browserInfo contains the fields that are marshalled into the Browser agent's
// info hash.
//
// https://newrelic.atlassian.net/wiki/spaces/eng/pages/50299103/BAM+Agent+Auto-Instrumentation
type browserInfo struct {
Beacon string `json:"beacon"`
LicenseKey string `json:"licenseKey"`
ApplicationID string `json:"applicationID"`
TransactionName string `json:"transactionName"`
QueueTimeMillis int64 `json:"queueTime"`
ApplicationTimeMillis int64 `json:"applicationTime"`
ObfuscatedAttributes string `json:"atts"`
ErrorBeacon string `json:"errorBeacon"`
Agent string `json:"agent"`
}
// BrowserTimingHeader encapsulates the JavaScript required to enable New
// Relic's Browser product.
type BrowserTimingHeader struct {
agentLoader string
info browserInfo
}
func appendSlices(slices ...[]byte) []byte {
length := 0
for _, s := range slices {
length += len(s)
}
combined := make([]byte, 0, length)
for _, s := range slices {
combined = append(combined, s...)
}
return combined
}
// WithTags returns the browser timing JavaScript which includes the enclosing
// <script> and </script> tags. This method returns nil if the receiver is
// nil, the feature is disabled, the application is not yet connected, or an
// error occurs. The byte slice returned is in UTF-8 format.
func (h *BrowserTimingHeader) WithTags() []byte {
withoutTags := h.WithoutTags()
if nil == withoutTags {
return nil
}
return appendSlices(browserStartTag, withoutTags, browserEndTag)
}
// WithoutTags returns the browser timing JavaScript without any enclosing tags,
// which may then be embedded within any JavaScript code. This method returns
// nil if the receiver is nil, the feature is disabled, the application is not
// yet connected, or an error occurs. The byte slice returned is in UTF-8
// format.
func (h *BrowserTimingHeader) WithoutTags() []byte {
if nil == h {
return nil
}
// We could memoise this, but it seems unnecessary, since most users are
// going to call this zero or one times.
info, err := json.Marshal(h.info)
if err != nil {
// There's no way to log from here, but this also should be unreachable in
// practice.
return nil
}
return appendSlices([]byte(h.agentLoader), browserInfoPrefix, info)
}
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