I'm curious as to why this particular scenario is occurring:
var obj = { 0:"bla", 1:"blabla" }
For some reason, when I try to access obj.0, an error is returned and I can only use obj[0]. Why is that the case?
I'm curious as to why this particular scenario is occurring:
var obj = { 0:"bla", 1:"blabla" }
For some reason, when I try to access obj.0, an error is returned and I can only use obj[0]. Why is that the case?
An acceptable naming identifier cannot begin with a number. It's a simple rule to follow. To access properties, you must use the dot notation if the keys are valid identifiers. Otherwise, you need to utilize square bracket notation like this: object['0']
object[0] is the same as object['0'] because property keys must be strings (any string can act as a key), so the value inside the brackets is automatically converted to a string.
Your code is encountering a SyntaxError because of a missing " after bla:
var obj = { 0:"bla", 1:"blabla" }
The reason why obj.0 results in a SyntaxError is because JavaScript recognizes property accesses using the syntax:
<identifier>.<identifier>
In JavaScript, identifiers cannot start with numbers. This is why trying to declare var 1a = 1; will lead to a SyntaxError due to an unexpected number.
Instead, by using obj[0], JavaScript interprets 0 as a string and accesses properties based on keys (which are strings) in associative arrays like this:
obj["constructor"]
For more information on identifier syntax in JavaScript, refer to section 7.6 of the ECMAScript Language Specification.
The excerpt below outlines the syntax for identifiers (extracted from the provided link):
IdentifierName ::
IdentifierStart
IdentifierName IdentifierPart
IdentifierStart ::
UnicodeLetter
$
_
\ UnicodeEscapeSequence
let object = { 0:'hello', 1:'world' } //incorrect
The string 'hello' is not enclosed in double quotes properly, so the right way to do it is:
let object = { 0:"hello", 1:"world" } //correct
Give this a shot:
set up
let data = { "0":"hello", "1":"world" };
retrieve
alert(data[0]);
alert(data[1]);
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