Add feature for readable timestamp string

Cargo.toml

@@ -10,12 +10,16 @@ keywords = ["pretty-printer", "ndjson", "femme", "log", "logger"]
 readme = "README.md"
 edition = "2018"
 
+[features]
+readable_timestamp = ["chrono"]
+
 [dependencies]
 log = { version = "0.4.7", features = ["kv_unstable", "std"] }
 serde = "1.0.97"
 serde_derive = "1.0.97"
 serde_json = "1.0.56"
 cfg-if = "0.1.9"
+chrono = { version = "0.4.19", optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 web-sys = { version = "0.3.25", features = ["console"] }

src/ndjson.rs

@@ -1,5 +1,7 @@
 //! Print logs as ndjson.
 
+#[cfg(readable_timestamp)]
+use chrono::prelude::*;
 use log::{kv, LevelFilter, Log, Metadata, Record};
 use std::io::{self, StdoutLock, Write};
 use std::time;
@@ -24,8 +26,26 @@ impl Log for Logger {
             let stdout = io::stdout();
             let mut handle = stdout.lock();
             let level = get_level(record.level());
-            let time = time::UNIX_EPOCH.elapsed().unwrap().as_millis();
-            write!(&mut handle, "{{\"level\":{},\"time\":{},\"msg\":", level, time).unwrap();
+            #[cfg(not(readable_timestamp))]
+            {
+                let time = time::UNIX_EPOCH.elapsed().unwrap().as_millis();
+                write!(
+                    &mut handle,
+                    "{{\"level\":{},\"time\":{},\"msg\":",
+                    level, time
+                )
+                .unwrap();
+            }
+            #[cfg(readable_timestamp)]
+            {
+                let time = Local::now().format("%Y-%m-%d %H:%M:%S%.f%z");
+                write!(
+                    &mut handle,
+                    "{{\"level\":{},\"time\":\"{}\",\"msg\":",
+                    level, time
+                )
+                .unwrap();
+            }
             serde_json::to_writer(&mut handle, record.args()).unwrap();
             format_kv_pairs(&mut handle, &record);
             writeln!(&mut handle, "}}").unwrap();