Javascript if variable is undefined then use another
2772
Is there a "null coalescing" operator in JavaScript?
84421
variable === undefined vs. typeof variable === "undefined"
95117
How do I pass variables to JavaScript?
134996
How can I temporarily disable the "return value might be undefined" warning?
105766
Load image if found, else load another image
91006
Why can I refer to a variable outside of an if/unless/case statement that never ran?
57688
How to name a variable with the value of another variable?
141836
How to use multiple jquery object variables as selectors?
113905
How can I check whether a variable is defined in JavaScript?
58571
how to pass a value to a variable that in a other variable
20165
How to initialize var?
68074
JavaScript 'in' operator for `undefined` elements in Arrays
122806
How to include a variable in another variable
107469
What is the best way to return an error from a function when I'm already returning a value?
146642
Using an if statement to check if a div is empty
144673
Why does this JavaScript code print "undefined" on the console?
92587
Surprised that global variable has undefined value in JavaScript