js isset variable code example

Example 1: javascript isset

if (typeof foo !== 'undefined') {
  
}

Example 2: isset js

if (typeof obj.foo !== 'undefined') {
}

Example 3: check if isset variable js

var status = 'Variable exists'

try {
  myVar
} catch (ReferenceError) {
  status = 'Variable does not exist'
}

console.log(status)