Why does nodejs print ... at terminal for destructuring assignment and how to install V8 to run JavaScript at terminal at *nix?

After reading Running V8 Javascript Engine Standalone decided to try installing V8 for the express purpose of running JavaScript at terminal.

Following guidance at Install depot_tools

$ sudo apt-get git
$ git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
$ export PATH=`pwd`/depot_tools:"$PATH"

Though have not yet built [V8][2]. Instead, first tried the suggestion at linked Question of using nodejs. Note, have limited experience with nodejs other than attempting to use nodejs to resolve How to test if jQuery 3.0 beta is Promises/A+ compatible in browser?

$ sudo apt-get install nodejs
> x = 10*5
50
> x
50
> let {id} = {id:123}
... 
... id
... 
> id
ReferenceError: id is not defined
    at repl:1:1
    at REPLServer.defaultEval (repl.js:252:27)
    at bound (domain.js:287:14)
    at REPLServer.runBound [as eval] (domain.js:300:12)
    at REPLServer.<anonymous> (repl.js:417:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:210:10)
    at REPLServer.Interface._line (readline.js:549:8)
    at REPLServer.Interface._ttyWrite (readline.js:826:14)
> {id} = {id:123}
ReferenceError: Invalid left-hand side in assignment
    at Object.exports.createScript (vm.js:24:10)
    at REPLServer.defaultEval (repl.js:225:25)
    at bound (domain.js:287:14)
    at REPLServer.runBound [as eval] (domain.js:300:12)
    at REPLServer.<anonymous> (repl.js:417:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:210:10)
    at REPLServer.Interface._line (readline.js:549:8)
    at REPLServer.Interface._ttyWrite (readline.js:826:14)
> x
50
> var y = 456
undefined
> y
456
> var [a, b] = [1,2] 
... a
... 

> function test(a = 123) {return a}
... test(5)
... 
... 

Questions:

• What is repl ?
• Why is nodejs not recognizing destructuring assignment at repl at terminal?
• What does ... mean at terminal when running nodejs?
• How to run JavaScript commands at terminal with nodejs, including for example destructuring assignment; default parameters; defining and calling functions; other common usages, which do not result in ...?
• How to correctly build V8 for purpose of running JavaScript at terminal?

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