Strange & annoying JSON behavior in ExtendScript.

Adobe Community Professional ,
Apr 12, 2021 Apr 12, 2021

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Hey everyone! I have spent far too long on JSON-related issues and finally I did a test which confirmed this weird issue and I am wondering if anyone knows a setting or answer for it.

The problem is, in the following JSX code I get a result where all empty objects and empty arrays are split into having a blank nextline between them.

I'm using the JSON object as pasted from Crockford's JSON (https://github.com/douglascrockford/JSON-js/blob/master/json2.js), and what I always get is in ExtendScript the bad newline, but when ran in the dev console of a browser it does no newline (i.e.: works like it's supposed to).

#target illustrator
function test() {

	if (typeof JSON !== "object") {
		JSON = {};
	}

	(function () {
		"use strict";

		var rx_one = /^[\],:{}\s]*$/;
		var rx_two = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g;
		var rx_three = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g;
		var rx_four = /(?:^|:|,)(?:\s*\[)+/g;
		var rx_escapable = /[\\"\u0000-\u001f\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
		var rx_dangerous = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;

		function f(n) {
			// Format integers to have at least two digits.
			return (n < 10)
				? "0" + n
				: n;
		}

		function this_value() {
			return this.valueOf();
		}

		if (typeof Date.prototype.toJSON !== "function") {

			Date.prototype.toJSON = function () {

				return isFinite(this.valueOf())
					? (
						this.getUTCFullYear()
						+ "-"
						+ f(this.getUTCMonth() + 1)
						+ "-"
						+ f(this.getUTCDate())
						+ "T"
						+ f(this.getUTCHours())
						+ ":"
						+ f(this.getUTCMinutes())
						+ ":"
						+ f(this.getUTCSeconds())
						+ "Z"
					)
					: null;
			};

			Boolean.prototype.toJSON = this_value;
			Number.prototype.toJSON = this_value;
			String.prototype.toJSON = this_value;
		}

		var gap;
		var indent;
		var meta;
		var rep;


		function quote(string) {

			// If the string contains no control characters, no quote characters, and no
			// backslash characters, then we can safely slap some quotes around it.
			// Otherwise we must also replace the offending characters with safe escape
			// sequences.

			rx_escapable.lastIndex = 0;
			return rx_escapable.test(string)
				? "\"" + string.replace(rx_escapable, function (a) {
					var c = meta[a];
					return typeof c === "string"
						? c
						: "\\u" + ("0000" + a.charCodeAt(0).toString(16)).slice(-4);
				}) + "\""
				: "\"" + string + "\"";
		}


		function str(key, holder) {

			// Produce a string from holder[key].

			var i;          // The loop counter.
			var k;          // The member key.
			var v;          // The member value.
			var length;
			var mind = gap;
			var partial;
			var value = holder[key];

			// If the value has a toJSON method, call it to obtain a replacement value.

			if (
				value
				&& typeof value === "object"
				&& typeof value.toJSON === "function"
			) {
				value = value.toJSON(key);
			}

			// If we were called with a replacer function, then call the replacer to
			// obtain a replacement value.

			if (typeof rep === "function") {
				value = rep.call(holder, key, value);
			}

			// What happens next depends on the value's type.

			switch (typeof value) {
				case "string":
					return quote(value);

				case "number":

					// JSON numbers must be finite. Encode non-finite numbers as null.

					return (isFinite(value))
						? String(value)
						: "null";

				case "boolean":
				case "null":

					// If the value is a boolean or null, convert it to a string. Note:
					// typeof null does not produce "null". The case is included here in
					// the remote chance that this gets fixed someday.

					return String(value);

				// If the type is "object", we might be dealing with an object or an array or
				// null.

				case "object":

					// Due to a specification blunder in ECMAScript, typeof null is "object",
					// so watch out for that case.

					if (!value) {
						return "null";
					}

					// Make an array to hold the partial results of stringifying this object value.

					gap += indent;
					partial = [];

					// Is the value an array?

					if (Object.prototype.toString.apply(value) === "[object Array]") {

						// The value is an array. Stringify every element. Use null as a placeholder
						// for non-JSON values.

						length = value.length;
						for (i = 0; i < length; i += 1) {
							partial[i] = str(i, value) || "null";
						}

						// Join all of the elements together, separated with commas, and wrap them in
						// brackets.

						v = partial.length === 0
							? "[]"
							: gap
								? (
									"[\n"
									+ gap
									+ partial.join(",\n" + gap)
									+ "\n"
									+ mind
									+ "]"
								)
								: "[" + partial.join(",") + "]";
						gap = mind;
						return v;
					}

					// If the replacer is an array, use it to select the members to be stringified.

					if (rep && typeof rep === "object") {
						length = rep.length;
						for (i = 0; i < length; i += 1) {
							if (typeof rep[i] === "string") {
								k = rep[i];
								v = str(k, value);
								if (v) {
									partial.push(quote(k) + (
										(gap)
											? ": "
											: ":"
									) + v);
								}
							}
						}
					} else {

						// Otherwise, iterate through all of the keys in the object.

						for (k in value) {
							if (Object.prototype.hasOwnProperty.call(value, k)) {
								v = str(k, value);
								if (v) {
									partial.push(quote(k) + (
										(gap)
											? ": "
											: ":"
									) + v);
								}
							}
						}
					}

					// Join all of the member texts together, separated with commas,
					// and wrap them in braces.

					v = partial.length === 0
						? "{}"
						: gap
							? "{\n" + gap + partial.join(",\n" + gap) + "\n" + mind + "}"
							: "{" + partial.join(",") + "}";
					gap = mind;
					return v;
			}
		}

		// If the JSON object does not yet have a stringify method, give it one.

		if (typeof JSON.stringify !== "function") {
			meta = {    // table of character substitutions
				"\b": "\\b",
				"\t": "\\t",
				"\n": "\\n",
				"\f": "\\f",
				"\r": "\\r",
				"\"": "\\\"",
				"\\": "\\\\"
			};
			JSON.stringify = function (value, replacer, space) {

				// The stringify method takes a value and an optional replacer, and an optional
				// space parameter, and returns a JSON text. The replacer can be a function
				// that can replace values, or an array of strings that will select the keys.
				// A default replacer method can be provided. Use of the space parameter can
				// produce text that is more easily readable.

				var i;
				gap = "";
				indent = "";

				// If the space parameter is a number, make an indent string containing that
				// many spaces.

				if (typeof space === "number") {
					for (i = 0; i < space; i += 1) {
						indent += " ";
					}

					// If the space parameter is a string, it will be used as the indent string.

				} else if (typeof space === "string") {
					indent = space;
				}

				// If there is a replacer, it must be a function or an array.
				// Otherwise, throw an error.

				rep = replacer;
				if (replacer && typeof replacer !== "function" && (
					typeof replacer !== "object"
					|| typeof replacer.length !== "number"
				)) {
					throw new Error("JSON.stringify");
				}

				// Make a fake root object containing our value under the key of "".
				// Return the result of stringifying the value.

				return str("", { "": value });
			};
		}


		// If the JSON object does not yet have a parse method, give it one.

		if (typeof JSON.parse !== "function") {
			JSON.parse = function (text, reviver) {

				// The parse method takes a text and an optional reviver function, and returns
				// a JavaScript value if the text is a valid JSON text.

				var j;

				function walk(holder, key) {

					// The walk method is used to recursively walk the resulting structure so
					// that modifications can be made.

					var k;
					var v;
					var value = holder[key];
					if (value && typeof value === "object") {
						for (k in value) {
							if (Object.prototype.hasOwnProperty.call(value, k)) {
								v = walk(value, k);
								if (v !== undefined) {
									value[k] = v;
								} else {
									delete value[k];
								}
							}
						}
					}
					return reviver.call(holder, key, value);
				}


				// Parsing happens in four stages. In the first stage, we replace certain
				// Unicode characters with escape sequences. JavaScript handles many characters
				// incorrectly, either silently deleting them, or treating them as line endings.

				text = String(text);
				rx_dangerous.lastIndex = 0;
				if (rx_dangerous.test(text)) {
					text = text.replace(rx_dangerous, function (a) {
						return (
							"\\u"
							+ ("0000" + a.charCodeAt(0).toString(16)).slice(-4)
						);
					});
				}

				// In the second stage, we run the text against regular expressions that look
				// for non-JSON patterns. We are especially concerned with "()" and "new"
				// because they can cause invocation, and "=" because it can cause mutation.
				// But just to be safe, we want to reject all unexpected forms.

				// We split the second stage into 4 regexp operations in order to work around
				// crippling inefficiencies in IE's and Safari's regexp engines. First we
				// replace the JSON backslash pairs with "@" (a non-JSON character). Second, we
				// replace all simple value tokens with "]" characters. Third, we delete all
				// open brackets that follow a colon or comma or that begin the text. Finally,
				// we look to see that the remaining characters are only whitespace or "]" or
				// "," or ":" or "{" or "}". If that is so, then the text is safe for eval.

				if (
					rx_one.test(
						text
							.replace(rx_two, "@")
							.replace(rx_three, "]")
							.replace(rx_four, "")
					)
				) {

					// In the third stage we use the eval function to compile the text into a
					// JavaScript structure. The "{" operator is subject to a syntactic ambiguity
					// in Javascript&colon; it can begin a block or an object literal. We wrap the text
					// in parens to eliminate the ambiguity.

					j = eval("(" + text + ")");

					// In the optional fourth stage, we recursively walk the new structure, passing
					// each name/value pair to a reviver function for possible transformation.

					return (typeof reviver === "function")
						? walk({ "": j }, "")
						: j;
				}

				// If the text is not JSON parseable, then a SyntaxError is thrown.

				throw new SyntaxError("JSON.parse");
			};
		}
	}());

	var sampleObj = {
		prop1: "A",
		prop2: "B",
		prop3: {
			item1: 1,
			item2: 2,
		},
		prop4: [],
		prop5: {},
	};

	var stringified = JSON.stringify(sampleObj);
	alert(stringified);
};
test();

 

Silly-V_0-1618261671738.png

 

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correct answers 1 Correct Answer

Adobe Community Professional , Apr 12, 2021 Apr 12, 2021
for some strange reason the nested ternary function are misbehaving, change them to traditional if-else does that work for you? if (partial.length === 0) { v = "[]"; } else if (gap) { v = ( "[\n" + gap + partial.join(",\n" + gap) + "\n" + mind + "]" ); } else { v = "[" + partial.join(",") + "]"; } if (partial.length === 0) { v = "{}"; } else if (gap) { ...

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Adobe Community Professional ,
Apr 12, 2021 Apr 12, 2021

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for some strange reason the nested ternary function are misbehaving, change them to traditional if-else

does that work for you?

jsonEmptyObjects.PNG

   if (partial.length === 0) {
       v = "[]";
   }
   else if (gap) {
        v = (
            "[\n"
            + gap
            + partial.join(",\n" + gap)
            + "\n"
            + mind
            + "]"
        );
    }
    else {
        v = "[" + partial.join(",") + "]";
    }

 

   if (partial.length === 0) {
       v = "{}";
   }
    else if (gap) {
        v = "{\n" + gap + partial.join(",\n" + gap) + "\n" + mind + "}";
    }
    else {
        v = "{" + partial.join(",") + "}";
    }

 

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Adobe Community Professional ,
Apr 12, 2021 Apr 12, 2021

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Wow what a great finding, and yet another reason to stay away from nested ternary functions! Thanks, now I'm going to edit my JSON I've been using forever by changing these lines. But also when instructing new scripters while JSX still lives, now we'll have to point them to the JSON resource and also now may wanna mention this change - but chances are hardly anyone is going to run into the case where it's even noticed, as I think you can read and write the bad newline JSON to files and from files, it's only when you want to send it by some means where the newlines are going to break some string command - in my case it was capturing stringified JSON objects as properties of a parent object that was also going to get stringified and then the whole thing was gonna get parsed by browser javascript, at which point the parse fails due to the unescaped nexlines. I was doing ok by just replacing different combinations of backslashes and quotes for a while but for my superior quality solutions, after the unsettling inner voice grows too loud, I always go here, where the action is!

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Adobe Community Professional ,
Apr 13, 2021 Apr 13, 2021

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I use ternary in its simplest form, I must admit, I didn't know how to nest them 🙂

 

I've used JSON for simple info passing as well, never had to pass empty objects before.

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Adobe Community Professional ,
Apr 13, 2021 Apr 13, 2021

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In my case there's complex objects which may or may not have properties populated, but instead of having a null, it has the empty object. This simplifies all the null checks when iterating over the items, if there are no items then it cancels itself out as an interation of 0.

 

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