Code that does not work: console.clear();

try {
  test(token);
}
catch(err) {
  console.log(err.toString());
}

if(typeof token === undefined) {
  console.log("token exists");
}

test(token);

if(token) {
  console.log("token exists");
}

function test(o) {
  if(o) {
      console.log("token exists");
  }
}

JSBin: ,js,console,output

Question: How can I test a 'token' for existence where it doesn't throw a reference error if it doesn't?

All three of my examples throw a ReferenceError: token is not defined

Code that does not work: console.clear();

try {
  test(token);
}
catch(err) {
  console.log(err.toString());
}

if(typeof token === undefined) {
  console.log("token exists");
}

test(token);

if(token) {
  console.log("token exists");
}

function test(o) {
  if(o) {
      console.log("token exists");
  }
}

JSBin: http://jsbin./qanuk/1/edit?html,js,console,output

Question: How can I test a 'token' for existence where it doesn't throw a reference error if it doesn't?

All three of my examples throw a ReferenceError: token is not defined

• javascript

Share Improve this question Follow asked May 28, 2014 at 19:40 Mike CheelMike Cheel 13.1k1010 gold badges7777 silver badges105105 bronze badges

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 9

Use:

if(typeof token === 'undefined')

• typeof is a keyword, not a function
• typeof always returns a string