Do closures capture objects by reference or by value in JavaScript?
By reference to the variable. If you mutate the object's properties, the closure sees the changes. If you reassign the variable to a new object, the closure sees the new object (because it references the variable, not the original object).
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More FAQs in Closures Capture the Variable, Not the Value in JavaScript
The variable. A closure holds a reference to the variable, not a snapshot of its value. If the variable changes before the callback runs, the closure sees the updated value. This is why var in a loop logs the final value.
Because they all close over the same variable i. Closures capture the variable, not the value. When the callbacks run, i is the final value, so all callbacks log it.
Use let (creates a fresh binding per iteration), or an IIFE that passes the current value as a parameter (pass-by-value for primitives), or pass the value as an extra argument to setTimeout.
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