Print Object like console.log (with a lot of information) in javascript

Question

I need to send an email that contains the console.log output of a JS object. Here a code example:

let array_multi = [];
array_multi["07:00"] = ["one","two","three"];
array_multi["08:00"] = ["foo","bar","foo"];
array_multi["09:00"] = ["lorem"];
console.log(array_multi);

In my console result like this:

Is there some method to get this output in plain text, or should I write a custom parsing function?

If you're doing this manually, the Firefox console lets you right-click on an Object that's been logged to the console, and you can select "Copy object". That will do the JSON conversion for you, so only JSON-serializable properties are included. — Pointy
– Pointy, Commented Mar 23, 2019 at 12:00
@Jonas Wilms yes I run inside a node js script and need variable with text for send w/ node mail extesion — r1si
– r1si, Commented Mar 23, 2019 at 12:33

ultrafez · Accepted Answer · 2020-06-28 00:09:25Z

5

If you are using JSON.stringify, you'll get the complete data, however there are a few downsides:

Arrays string properties, functions and other data structures get ignored completely (therefore serializing your data as is won't work¹)
circular references fail to serialize
There is no way to see inheritance from that

In your case you could do:

let array_multi = {};
array_multi["07:00"] = ["one","two","three"];
array_multi["08:00"] = ["foo","bar","foo"];
array_multi["09:00"] = ["lorem"];

// logs as object
console.log(array_multi);
console.log(typeof array_multi);

// parse and convert to string
console.log(JSON.stringify(array_multi)); 
console.log(typeof JSON.stringify(array_multi));

In Node.js you've got another option, which is util.format, which will return the same content as a string that you can see in the Node.js console. While it does give you a great insight into the different datatypes and relationships, it cannot show you the same infinite tree that an interactive console is able to show, so it will only show you a small part of the big picture.

¹: Your array_multi should actually be an object, not an array, as arrays should only have numeric keys.

edited Jun 28, 2020 at 0:09

ultrafez

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answered Mar 23, 2019 at 11:50

Nino Filiu

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3 Comments

Nino Filiu Over a year ago

Why the downvote? I precisely answers the OP's question.

Nino Filiu Over a year ago

I am using the OP's data while precising that it should be an object instead of an array

Pointy Over a year ago

Yes yes sorry, I saw that. (I didn't downvote.) I think this is probably the best the OP can do, but it should be noted that not all object graphs can be serialized as JSON. (Well a custom serializer would be the next step I guess.)

r1si · Accepted Answer · 2019-03-23 17:05:43Z

After a lot of search the right method is write a custom function (chrome have once inside dev tools core)
here the solution:

let array_multi = [];
array_multi["07:00"] = ["one","two","three"];
array_multi["08:00"] = ["foo","bar","foo"];
array_multi["09:00"] = ["lorem"];


function print_js_element(elm, show_content = false){
	
	let output_res = "{\n";


	let object_keys = Object.keys(elm);

	object_keys.some(function(key,index) {

		output_res += "\t" + key + ": (" + elm[key].length + ")";

		if(show_content){
			output_res += " " + JSON.stringify(elm[key]);
		}

		output_res += "\n";
	});

	output_res += "\n}";
	return output_res;

}


console.log(print_js_element(array_multi,false));
console.log(print_js_element(array_multi,true));

Vardan Gupta · Accepted Answer · 2019-03-23 12:11:15Z

-1

Covert this array into an object first:

let array_multi = [];
array_multi["07:00"] = ["one","two","three"];
array_multi["08:00"] = ["foo","bar","foo"];
array_multi["09:00"] = ["lorem"];

let arrObj = {...array_multi};

console.log(JSON.stringify(arrObj));

answered Mar 23, 2019 at 12:11

Vardan Gupta

893 bronze badges

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