Object vs Array

Question

While typing the value {2,4,45,50} on console displays 50, but assigning the {2,4,45,50} to variable getting the error

 var a = {2,4,45,50}
 Uncaught SyntaxError: Unexpected number

What is the concept on this.

• skara9: its [] for arrays, the console just treats your {} like a block and gives you the last value
• Raptor: @govinda Do you mean var a = [2, 4, 45, 50]?
• Govinda raj: in that case why are we getting the error on assign to variable , should set 50 to the variable as per my understanding
• Gert B.: It is not a valid json object, you cannot just put numbers in a JSON
• skara9: @Govindaraj {1, 2, 3} does not make an array in JS, nor is it a valid expression, so of course assigning it to a variable will throw -- the {} creates a block, or a set of statements, and the console typically gives you the last value when given a set of expressions -- even typing 1, 2, 3, 4, 5 into the console yields 5

Answer 1

its [] for arrays, the console just treats your {} like a block and gives you the last value – skara9

As Skara mentioned, [] is for arrays. {} is for tables, so when you assign it to a variable since it's a table it's expecting a key and value, for example: {a: 1, b:2, 3:4}. If you want an array then change {} to [], otherwise, you should assign a key and value for the table.

If you would like to log a specific value of an array you can do so using an index, index starts from 0 to the number of values. For example:

 var a = [2,4,45,50]
 console.log(a[0])
 //Expected output is 2

If you wanted to use a table and log the value of the first key, which in this case would be a, then you would do:

 var test = {a:2, b:4, c:45, d:50}
 console.log(test.a)
 //Expected output is 2 because 2 is assigned to a

You could also just log the whole array and/or table.