Shorthand function for checking whether a property exists
21050
Test for existence of nested JavaScript object key
91447
Check if a method exists
5307
Check if a variable is in an ad-hoc list of values
6288
How do I check if an object has a specific property in JavaScript?
144136
jQuery: Check if image exists
128669
How to check whether multiple values exist within an Javascript array
110541
How to check whether dynamically attached event listener exists or not?
58722
Node.js - Mongoose - Check if a collection exists
49796
How to access object properties with names like integers?
134748
Determine whether an array contains a value
148273
Check if event exists on element
137138
How to check if an array element exists?
155283
Best way to check if object exists in Entity Framework?
70566
How do I check if an object has a key in JavaScript?
1949
How do I check whether a file exists without exceptions?
49696
Checking it see if a file exists in a script
157008
Check if counter exists