Json name value pairs

MartinRinehart

@martinrinehart said:

JSON is JavaScript. Given that x is a valid JSON object, eval( 'foo =' + x ) is all you need.

Nonsense.

Chris, that's most unkind. Take two Doug Crockfords and get back to me with a counter example.

chrisglasier

@martinrinehart said:

Chris, that's most unkind. Take two Doug Crockfords and get back to me with a counter example.

Sorry, maybe I've missed something but please explain evaluating a string + an object. What I have shown before works. It gives me the name value pairs as the caption.

Doug Crockfords are biscuits like Prince Charles's Duchy Originals?

Happy new year!

Chris

tbd


var db = {
	"projects"; [
	{
		"type"; "Head",
		"genus"; "Project",
		"name"; "House01",
		"link"; [3],
		"all"; [5,6]
	},
	{
		"type"; "Head",
		"genus"; "Project",
		"name"; "House02",
		"link"; [3],
		"all"; [5,6]
	}
	]
}

eval(db)                 
for (x in db.projects) {
	alert(db.projects[x].name)
}

Doug Crockford is the inventor of JSON. take a look also on javascript the good parts

check this fun:

alert(0.1+0.2) 
=> 0.30000000000000004

thomthom

@unknownuser said:

check this fun:

alert(0.1+0.2) 
> => 0.30000000000000004

wtf?

tbd

@thomthom said:

wtf?

if it is floats involved dont trust anyone

alert((0.1+0.2).toPrecision(2))
=> 0.30

MartinRinehart

@unknownuser said:

Doug Crockford is the inventor of JSON. take a look also on javascript the good parts

Didn't know he was on youtube, but the two Dougs I had in mind were JSON.org and the book JavaScript-The Good Parts.

JSON, Chris, was not defined by Crockford; it was discovered by Crockford lurking inside Eich's sometimes quirky, sometimes brilliant language. JSON is, by its definition, the syntax JavaScript uses to describe objects. Therefore

eval( 'foo = ' + json );

is valid JavaScript.

Oddly, my first attempt at this failed. I tried:

foo = eval( json );

If you got it running without eval() in anything like a general way you've done great work. Crockford is also famous for saying " eval() is evil".

MartinRinehart

@thomthom said:

wtf?

Your complete fluency in my native tongue never ceases to amaze me!

chrisglasier

@unknownuser said:

Doug Crockford is the inventor of JSON.

Yes yes ... I was just making sure two nonsenses don't make a sense.

Dan Rathbun

@chrisglasier said:

@unknownuser said:

Doug Crockford is the inventor of JSON.

Yes yes ... I was just making sure two nonsenses don't make a sense.

2(-1) = -2
so
2(nonsense) = non-twosenses

but:
(-1)^2 = 1
so
nonsense^2 = a sense

it follows then that:
the squareroot of nonsense must be imaginary

chrisglasier

@martinrinehart said:

.... JSON is, by its definition, the syntax JavaScript uses to describe objects. Therefore

eval( 'foo = ' + json );

is valid JavaScript.

Oddly, my first attempt at this failed. I tried:

foo = eval( json );

If you got it running without eval() in anything like a general way you've done great work.

If you say given 'that json is a valid JSON object' it means to my novice ears that the text written using jsonotation has already been eval'd or parsed.

In my case it gets parsed when it is imported as an object from a text file.

That's all!

Jim

Right - eval gets passed String objects. So before the eval is called, json is a variable which references a String.

After the eval, the variable foo refers to a Javascript Object.

However,

@unknownuser said:

To convert a JSON text into an object, you can use the eval() function. eval() invokes the JavaScript compiler. Since JSON is a proper subset of JavaScript, the compiler will correctly parse the text and produce an object structure. The text must be wrapped in parens to avoid tripping on an ambiguity in JavaScript's syntax.

var myObject = eval('(' + myJSONtext + ')');

and

@unknownuser said:

..If the server is not rigorous in its JSON encoding, or if it does not scrupulously validate all of its inputs, then it could deliver invalid JSON text that could be carrying dangerous script. The eval function would execute the script, unleashing its malice.

To defend against this, a JSON parser should be used. A JSON parser will recognize only JSON text, rejecting all scripts. In browsers that provide native JSON support, JSON parsers are also much faster than eval. It is expected that native JSON support will be included in the next ECMAScript standard.

var myObject = JSON.parse(myJSONtext, reviver);

I believe Chris is using json2.js on my recommendation, which is based on DC's recommendation because it is possible CG's data could come from an outside source.

And I would also repeat what TBD said and watch the "Good Stuff" video - at least you will know what to avoid in Javascript to make your life easier.