Truthy a Falsey values javascript

Truthy values and falsey values in a boolean context.

many codes to check if an variable has a value is like this.

let someVar;

if(someVar !== nil && someVar !== undefined && someVar !== '') {
  console.log('variable has a value');
}

you can refactor it to like this

  let someVar;

  if(someVar) {
    console.log('Variable has a value');
  }

but you must be aware of what evalute to to fase and what is evaluated to true

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Evaluate to fase

• null
• undefined
• 0
• Empty String
• false
• NaN

Evalute to true

• Empty Object {}
• Empty array []
• Negative number -5

you must be sure what kind of value the variable will store.