The console and breakpoints

Key points

1. 1Pick the console call by what you need to see: table for arrays of objects, dir for an object's properties, trace for the call path, count for how often.
2. 2console.assert prints only when its condition is false, and console.time with timeEnd measures the time between two calls with the same label.
3. 3In Chrome a logged object is shown live: when you expand it later, the console shows its current values. Log a copy or a string for a snapshot.
4. 4A conditional breakpoint pauses only when its expression is true. A logpoint prints a message without pausing. Neither needs a code change.
5. 5The debugger statement pauses like a breakpoint only while DevTools or another debugger is attached; otherwise it does nothing.