CODEWITHSUNDEEP
javascriptboolean
Nathan Jones
Nathan Jones

Reputation: 5144

How to use JavaScript logical operator for object property?

Is there a way to use a logical operator for object properties? For example, can I do something like:

var myObj = {};
var prop = myObj.prop || 0;

Where prop gets set to 0 if prop isn't a property of myObj? But here,

var myObj = {};
myObj.prop = 2;
var prop = myObj.prop || 0;

myObj.prop is set to 2 because prop exists in this case.

Upvotes: 1

Views: 600

Answers (4)

PatAtCP
PatAtCP

Reputation: 587

A simpler varient would be to set the property in your fallback

var prop = myObject.prop || (myObject.prop = 0);

Upvotes: 0

Sean Vieira
Sean Vieira

Reputation: 159875

No, but you can use the ternary conditional operator for it:

var has = Object.prototype.hasOwnProperty;
var prop = has.call(myObj, 'prop') ? 0 : undefined;

It is not perfect (future references to prop will no longer be a ReferenceError in the event that myObj does not have a prop property), but there is no better way without using let:

if (!has(...)) {
  let prop = 0;
  // Do things with `prop` here
}
// prop is still a ReferenceError outside of the if block

Upvotes: 2

Matt
Matt

Reputation: 20776

var prop = myObj.hasOwnProperty('prop') ? myObj.prop : 0

Upvotes: 2

Suman Bogati
Suman Bogati

Reputation: 6349

You could do something like this. You can use hasOwnProperty method to check that object has property or not

 var myObj = {};
 var prop = myObj.hasOwnProperty('prop') || 0;

Upvotes: 0

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