AlgoDaily - Implement JSON.parse

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The Final Code: Putting It All Together

Here's the complete function. It incorporates all the above steps to make a fully functional JSON parser in JavaScript.

JAVASCRIPT

1function parseJSON(input) {
2    // Edge Cases and Error Handling
3    if (input === "" || input[0] === "'") {
4        throw Error("Invalid JSON string");
5    }
6    if (input === "null") { return null; }
7    if (input === "{}") { return {}; }
8    if (input === "[]") { return []; }
9    if (input === "true") { return true; }
10    if (input === "false") { return false; }
11
12    // Parsing Strings
13    if (input[0] === '"') {
14        return input.slice(1, -1);
15    }
16
17    // Parsing Objects
18    if (input[0] === "{") {
19        return input
20            .slice(1, -1)
21            .split(",")
22            .reduce((acc, item) => {
23                const index = item.indexOf(":");
24                const key = item.slice(0, index);
25                const value = item.slice(index + 1);
26                acc[parseJSON(key)] = parseJSON(value);
27                return acc;
28            }, {});
29    }
30
31    // Parsing Arrays
32    if (input[0] === "[") {
33        return input
34            .slice(1, -1)
35            .split(",")
36            .map((x) => parseJSON(x));
37    }
38}