So I have to go through a bunch of code to get some data from an iframe. the iframe has a lot of data but in there is an object called '_name'. the first key of name is 'extension_id' and its value is a big long string. the json object is enclosed in apostrophes. I have tried removing the apostrophes but still instead of 'extension_id_output' I get a single curly bracket. the json object looks something like this
Frame {
...
...
_name: '{"extension_id":"a big huge string that I need"} "a bunch of other stuff":"this is a valid json object as confirmed by jsonlint", "globalOptions":{"crev":"1.2.50"}}}'
}
it's a whole big ugly paragraph but I really just need the extension_id. so this is the code I'm currently using after attempt 100 or whatever.
var frames = await page.frames();
// I'm using puppeteer for this part but I don't think that's relevant overall.
var thing = frames[1]._name;
console.log(frames[1])
// console.log(thing)
thing.replace(/'/g, '"')
// this is to remove the apostrophes from the outside of the object. I thought that would change things before. it does not. still outputs a single {
JSON.parse(thing)
console.log(thing[0])
instead of getting a big huge string that I need or whatever is written in extension_id. I get a {. that's it. I think that is because the whole object starts with a curly bracket. this is confirmed to me because console.log(thing[2]) prints e. so what's going on? jsonlint says this is a valid json object but maybe it's just a big string and I should be doing some kind of split to grab whaat's between the first : and the first ,. I'm really not sure.
For two reasons:
object[0] doesn't return the value an object's "first property", it returns the value of the property with the name "0", if any (there probably isn't in your object); and
Because it's JSON, and when you're dealing with JSON in JavaScript code, you are by definition dealing with a string. (More here.) If you want to deal with the object that the JSON describes, parse it.
Here's an example of parsing it and getting the value of the extension_id property from it:
const parsed = JSON.parse(frames[1]._name);
console.log(parsed.extension_id); // The ID
Related
TypeScript does not produce any errors for the following code:
const maybe_a_string: undefined | string = undefined;
const false_or_string: false | string = false;
// I'd like the following to produce an error/warning...
const message_string = `Some readable string info should be here: ${maybe_a_string} ${false_or_string}`;
Is there some kind of setting I can turn on, or simple alternative ways to write the last line that will warn me about trying to use non-string variables inside strings like this? (but without needing to add extra lines of code for every sub-string to be asserted individually)
I guess it treats them as fine because some types like bools, numbers and misc objects have a .toString() method...
But especially in the case of undefined (which actually doesn't have a .toString() method) - it's quite common for you to have a bug there, as the only time you really want to see the string "undefined" inside another string is for debugging purposes. But there's a lot of these bugs out there in the wild where end users are seeing stuff like "hello undefined" unintentionally.
Personally I would handle this by making the string template into a function. That way you can specify that the arguments must be strings.
const createMessageString = (first: string, second: string): string => {
return `Some readable string info should be here: ${first} ${second}`;
}
const message_string = createMessageString( maybe_a_string, false_or_string );
// will give an error unless types are refined
Vote for https://github.com/microsoft/TypeScript/issues/30239 [Restrict template literal interpolation expressions to strings]
Additionally, you can try workarounds from the issue comments.
I have a very trivial problem, and I'm having trouble finding similar questions. On my Node JS server, I prepare an object of key-value pairs. The keys that have spaces in them are converted to strings like this {'key':'value'}. However, the keys without spaces or special characters don't have quotes surrounding them. When I print it out it looks like this {key:'value'}. The problem is, when I send the response back to the client, the keys without surrounding quotes are missing from the object. So how would I surround all the keys with quotes then so that it is sent properly?
JSON Objects must follow the RFC-7159, the easiest way to get a RFC-compliant JSON object is to use JSON.stringify on the object you want to output on your server side, which is natively supported in NodeJS.
You just need to convert the response to client by converting the javascript object to JSON object.
var object = { key: 'value' };
var newObject = JSON.stringify(object);
console.log("format : ", newObject);
//the JSON.stringify() function definition, it will simply turn the object log into a JSON string.
OUTPUT:
format : '{ 'key' : 'value' }'
I see a very weird problem when json when used in nodejs, it is skipping single quote from revision key . I want to pass this json as input to node request module and since single quote is missing from 'revision' key so it is not taking as valid json input. Could someone help how to retain it so that I can use it. I have tried multiple attempts but not able to get it correct.
What did I try ?
console.log(jsondata)
jsondata = {
'splits': {
'os-name': 'ubuntu',
'platform-version': 'os',
'traffic-percent': 100,
'revision': 'master'
}
}
Expected :-
{ splits:
{ 'os-name': 'ubuntu',
'platform-version': 'os',
'traffic-percent': 100,
'revision': 'master'
}
}
But in actual output single quote is missing from revision key :-
{ splits:
{ 'os-name': 'ubuntu',
'platform-version': 'os',
'traffic-percent': 100,
revision: 'master'
}
}
Run 2 :- Tried below code this also produce same thing.
data = JSON.stringify(jsondata)
result = JSON.parse(data)
console.log(result)
Run 3:- Used another way to achieve it
jsondata = {}
temp = {}
splits = []
temp['revision'] = 'master',
temp['os-name'] = 'ubuntu'
temp['platform-version'] = 'os'
temp['traffic-percent'] = 100
splits.push(temp)
jsondata['splits'] = splits
console.log(jsondata)
Run 4: tries replacing single quotes to double quotes
Run 5 : Change the order of revision line
This is what is supposed to happen. The quotes are kept only if the object key it’s not a valid JavaScript identifier. In your example, the 'splits' & 'revision' don't have a dash in their name, so they are the only ones with the quotes removed.
You shouldn't receive any error using this object - if you do, update this post mentioning the scenario and the error.
You should note that JSON and JavaScript are not the same things.
JSON is a format where all keys and values are surrounded by double quotes ("key" and "value"). A JSON string is produced by JSON.stringify, and is required by JSON.parse.
A JavaScript object has very similar syntax to the JSON file format, but is more flexible - the values can be surrounded by double quotes or single quotes, and the keys can have no quotes at all as long as they are valid JavaScript identifiers. If the keys have spaces, dashes, or other non-valid characters, then they need to be surrounded by single quotes or double quotes.
If you need your string to be valid JSON, generate it with JSON.stringify. If it's OK for it to be just valid JavaScript, then it's already fine - it does not matter whether the quotes are there or not.
If, for some reason, you need some imaginary third option (perhaps you are interacting with an API where someone has written their own custom string parser, and they are demanding that all keys are surrounded by single quotes?) you will probably need to write your own little string generator.
I am doing 2player game and when I get informations from server, it's in format "topic;arg1;arg2" so if I am sending positions it's "PlayerPos;x;y".
I then use split method with character ";".
But then... I even tried to write it on screen "PlayerPos" was written right, but it cannot be gained through if.
This is how I send info on server:
server.write("PlayerPos;"+player1.x+";"+player1.y);
And how I accept it on client:
String Get=client.readString();
String [] Getted = split(Get, ';');
fill(0);
text(Get,20,20);
text(Getted[0],20,40);
if(Getted[0]=="PlayerPos"){
text("HERE",20,100);
player1.x=parseInt(Getted[1]);
player1.x=parseInt(Getted[2]);
}
It writes me "PlayerPos;200;200" on screen, even "PlayerPos" under it. But it never writes "HERE" and it never makes it into the if.
Where is my mistake?
Don't use == when comparing String values. Use the equals() function instead:
if(Getted[0].equals("PlayerPos")){
From the Processing reference:
To compare the contents of two Strings, use the equals() method, as in if (a.equals(b)), instead of if (a == b). A String is an Object, so comparing them with the == operator only compares whether both Strings are stored in the same memory location. Using the equals() method will ensure that the actual contents are compared. (The troubleshooting reference has a longer explanation.)
I'm fairly new to groovy, looking at some existing code, and I see this:
def timestamp = event.timestamp[]
I don't understand what the empty square brackets are doing on this line. Note that the timestamp being def'd here should receive a long value.
In this code, event is defined somewhere else in our huge code base, so I'm not sure what it is. I thought it was a map, but when I wrote some separate test code using this notation on a map, the square brackets result in an empty value being assigned to timestamp. In the code above, however, the brackets are necessary to get correct (non-null) values.
Some quick Googling didn't help much (hard to search on "[]").
EDIT: Turns out event and event.timestamp are both zero.core.groovysupport.GCAccessor objects, and as the answer below says, the [] must be calling getAt() on these objects and returning a value (in this case, a long).
The square brackets will invoke the underlying getAt(Object) method of that object, so that line is probably invoking that one.
I made a small script:
class A {
def getAt(p) {
println "getAt: $p"
p
}
}
def a = new A()
b = a[]
println b.getClass()
And it returned the value passed as a parameter. In this case, an ArrayList. Maybe that timestamp object has some metaprogramming on it. What does def timestamp contains after running the code?
Also check your groovy version.
Empty list, found this. Somewhat related/possibly helpful question here.
Not at a computer, but that looks like it's calling the method event.timestamp and passing an empty list as a parameter.
The same as:
def timestamp = event.timestamp( [] )