Json first object is a *, how to get it?

Question

If I run:

$("#results ul").append(data.parse.langlinks.map(function(val){ return "<li>" + val.lang + "</li>" }));

I get all correct values of lang but I need to get the first object and it doesn't have a verbal naming but it has

*

So when I try to access it like val.* I get:

Uncaught SyntaxError: Unexpected token *

JsFiddle

score 3 · Accepted Answer · answered Jul 25 '17 at 23:34

3

Access your object like this: val['*'] .

answered Jul 25 '17 at 23:34

Superdrac

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1

ha! No way, I was using double `" "` ! Thank you – rob.m Jul 25 '17 at 23:35
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Double quotes work as well, both are valid string delimiters. – DarthJDG Jul 25 '17 at 23:37
@DarthJDG yes sure but it was within a `.append` which was already using `double quotes`. Sight! – rob.m Jul 25 '17 at 23:42
I meant on my real case scenario not on here as we don't have `double quotes` on the `.append` used on the question on here. – rob.m Jul 25 '17 at 23:54

ryanpcmcquen · Answer 2 · 2017-07-25T23:50:05.770

2

You need to use bracket notation when accessing objects containing special characters:

return val['*'] + "</li>";

https://jsfiddle.net/ryanpcmcquen/fg395Lp9/

It's also worth noting that you need to use bracket notation when accessing an object using a variable or a reserved keyword (thanks to @DarthJDG for pointing that out):

var foo = '*';
return val[foo];

Furthermore, if you are exploring some newer aspects of JavaScript, computed property names incorporate bracket notation:

https://ryanpcmcquen.org/javascript/2016/10/25/computed-property-names-are-awesome.html

edited Jul 25 '17 at 23:50

answered Jul 25 '17 at 23:35

ryanpcmcquen

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Worth noting that you also need to use bracket notation if the property name is a reserved keyword, e.g. `class`. – DarthJDG Jul 25 '17 at 23:42
1

Thank you @DarthJDG, I have added that. – ryanpcmcquen Jul 25 '17 at 23:45
@DarthJDG does it mean it should be `val['lang']` rather than `val.lang`? – rob.m Jul 25 '17 at 23:47
@ryanpcmcquen the above answer has no quotes, would it work the same? – rob.m Jul 25 '17 at 23:48
@rob.m, no `val.lang` is perfectly valid since there are no breaking special characters. It is a _valid_ identifier: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_Accessors – ryanpcmcquen Jul 25 '17 at 23:49
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@rob.m, when using bracket notation without quotes, you are providing a variable. I expanded my example to make that more obvious. – ryanpcmcquen Jul 25 '17 at 23:50
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@ryanpcmcquen perfect, makes sense. Thanks for this – rob.m Jul 25 '17 at 23:51
1

@rob.m you are welcome! – ryanpcmcquen Jul 25 '17 at 23:52

score 1 · Answer 3 · answered Jul 25 '17 at 23:45

My answer is the same as the others, but with a bit more explanation...

val["*"]  // Bracket notation

Objects in JavaScript are really not too much more than dictionaries, groupings of key/value pairs or, said another way, associative arrays.

As such, you are always able to access an object's property (a.k.a. key) by passing a string as an index to the object. But, if the index/key/property name does not contain any illegal language identifier characters, then you can use the more common "dot notation".

Taking this to an extreme, most people would probably say that an object property name could not contain spaces because, of course, this wouldn't compile and doesn't seem to make any sense:

 obj.some property name = "10";    // won't compile

But, you actually can have a property name that contains spaces if you think of the object as an array and the property name as a key:

 obj["some property name"] = 10;  // perfectly fine

This also opens up some great opportunities for dynamic code because it allows for you to pass a key (string) dynamically:

var keyName = new Date().toLocaleTimeString();
    
var obj = {};
obj[keyName] = "some value";
     
for(var prop in obj){ 
     console.log("The obj." + prop + " property has a value of: " + obj[prop]);
}

Json first object is a *, how to get it?

3 Answers3