Solution
Our solution would be the method stringify, that will simply handle the cases we mentioned above, with many different if conditions. For example, we return undefined if the type of the data is a function, or we return null if it is a synbol, undefined, infinity, or null.
1if (typeof data === "function") {
2 return undefined;
3}
4if (data === Infinity || data === -Infinity || data === null
5 || data === undefined || typeof data === "symbol") {
6 return "null";
7}If the data is a string, number or a boolean, we return the data itself, bearing in mind the quotes needed for a string value.
1if (typeof data === "string") {
2 return `"${data}"`;
3}
4if (typeof data === "number" || typeof data === "boolean") {
5 return `${data}`;
6}If our data type is a date, as stated above, we return it as a string, by using data.toISOString().
In case we are dealing with an array, or an object, then we need a bit more logic to parse our data. So, for an array, we will first map and stringify our data to make sure the elements are all in a string format, and then we are going to parse it in the needed JSON array format, using braces, and separate the data with commas:
1if (Array.isArray(data)) {
2 const arr = data.map((el) => stringify(el));
3 return `[${arr.join(",")}]`;
4}For objects, we will handle them by looping the object properties one by one, and then using the reduce method we will divide them into key-value pairs - key being the property name, and the value being its value. We will perserve the JSON objects notation, wrapping the object properties into brackets, and in the format "key": "value".
1if (typeof data === "object") {
2 const arr = Object.entries(data).reduce((acc, [key, value]) => {
3 if (value === undefined) {
4 return acc;
5 }
6 acc.push(`"${key}":${stringify(value)}`);
7 return acc;
8 }, []);
9 return `{${arr.join(",")}}`;
10}Our final solution with all these conditions handled would look like this:
1function stringify(data) {
2 if (typeof data === "string") {
3 return `"${data}"`;
4 }
5 if (typeof data === "function") {
6 return undefined;
7 }
8 if (data === Infinity || data === -Infinity || data === null
9 || data === undefined || typeof data === "symbol") {
10 return "null";
11 }
12 if (typeof data === "number" || typeof data === "boolean") {
13 return `${data}`;
14 }
15
16 if (data instanceof Date) {
17 return `"${data.toISOString()}"`;
18 }
19 if (Array.isArray(data)) {
20 const arr = data.map((el) => stringify(el));
21 return `[${arr.join(",")}]`;
22 }
23 if (typeof data === "object") {
24 const arr = Object.entries(data).reduce((acc, [key, value]) => {
25 if (value === undefined) {
26 return acc;
27 }
28 acc.push(`"${key}":${stringify(value)}`);
29 return acc;
30 }, []);
31 return `{${arr.join(",")}}`;
32 }
33}