How to Implement a JSON.stringify

When implementing a JSON.stringify function, we need to consider several key points: properly handling different data types (such as strings, numbers, objects, and arrays), handling circular references and other edge cases, and ensuring the resulting string is correctly formatted. We will now implement a simplified version of JSON.stringify step by step.\n\n### Step 1: Basic Type Handling\nFor basic data types, handling is relatively straightforward:\n- Numbers: Convert directly to their string representation.\n- Strings: Enclose in quotes and handle special characters, such as escape characters.\n- Boolean values: Convert to "true" or "false".\n- null: Return "null" directly.\n\n### Step 2: Arrays and Objects\nFor arrays and objects, we need to recursively process their internal elements:\n- Arrays: Iterate over each element, apply stringify to each, join the results with commas, and finally enclose with [].\n- Objects: Iterate over each enumerable property, apply stringify to both the key and value, join the results with colons and commas, ensure key names are enclosed in quotes, and finally enclose with {}.\n\n### Step 3: Special Cases Handling\n- undefined, functions, and symbols: These types are not allowed in JSON; they should typically return undefined or be converted to null in arrays.\n- Circular references: Maintain a record of visited objects; if a circular reference is detected, throw an error or handle it differently.\n\n### Example Implementation\nHere is a simplified example implementation that includes only basic functionality:\n\njavascript\nfunction jsonStringify(obj) {\n const type = typeof obj;\n if (type !== 'object' || obj === null) {\n // Return text directly for non-objects or null\n if (type === 'string') obj = '"' + obj + '"';\n return String(obj);\n } else {\n const json = [];\n const isArray = Array.isArray(obj);\n for (const key in obj) {\n let value = obj[key];\n const valueType = typeof value;\n if (valueType === 'string') {\n value = '"' + value + '"';\n } else if (valueType === 'object' && value !== null) {\n value = jsonStringify(value);\n }\n json.push((isArray ? \"\" : \"\" + key + \"\":\") + String(value));\n }\n return (isArray ? \"[\" : \"{\") + String(json) + (isArray ? \"}\" : \"]\");\n }\n}\n\n\n### Test Example\njavascript\nconsole.log(jsonStringify({ x: 5, y: 6 })); // Output: {\"x\":5,\"y\":6}\nconsole.log(jsonStringify([1, \"false\", false])); // Output: [1,\"false\",false]\nconsole.log(jsonStringify({ x: [10, undefined, function(){}, Symbol('')] })); // Output: {\"x\":[10,null,null,null]}\n\n\nThis implementation is very basic and does not handle many complex cases such as Date objects, RegExp objects, BigInt, and circular references. In actual development, additional handling logic and optimizations should be added based on specific requirements."}.content VM3446:1 Uncaught SyntaxError: Unexpected token ':' const xx = {"title":"How to Implement a JSON.stringify","content":"When implementing a JSON.stringify function, we need to consider several key points: properly handling different data types (such as strings, numbers, objects, and arrays), handling circular references and other edge cases, and ensuring the resulting string is correctly formatted. We will now implement a simplified version of JSON.stringify step by step.\n\n### Step 1: Basic Type Handling\nFor basic data types, handling is relatively straightforward:\n- Numbers: Convert directly to their string representation.\n- Strings: Enclose in quotes and handle special characters, such as escape characters.\n- Boolean values: Convert to "true" or "false".\n- null: Return "null" directly.\n\n### Step 2: Arrays and Objects\nFor arrays and objects, we need to recursively process their internal elements:\n- Arrays: Iterate over each element, apply stringify to each, join the results with commas, and finally enclose with [].\n- Objects: Iterate over each enumerable property, apply stringify to both the key and value, join the results with colons and commas, ensure key names are enclosed in quotes, and finally enclose with {}.\n\n### Step 3: Special Cases Handling\n- undefined, functions, and symbols: These types are not allowed in JSON; they should typically return undefined or be converted to null in arrays.\n- Circular references: Maintain a record of visited objects; if a circular reference is detected, throw an error or handle it differently.\n\n### Example Implementation\nHere is a simplified example implementation that includes only basic functionality:\n\njavascript\nfunction jsonStringify(obj) {\n const type = typeof obj;\n if (type !== 'object' || obj === null) {\n // Return text directly for non-objects or null\n if (type === 'string') obj = '"' + obj + '"';\n return String(obj);\n } else {\n const json = [];\n const isArray = Array.isArray(obj);\n for (const key in obj) {\n let value = obj[key];\n const valueType = typeof value;\n if (valueType === 'string') {\n value = '"' + value + '"';\n } else if (valueType === 'object' && value !== null) {\n value = jsonStringify(value);\n }\n json.push((isArray ? \"\" : \"\" + key + \"\":\") + String(value));\n }\n return (isArray ? \"[\" : \"{\") + String(json) + (isArray ? \"}\" : \"]\");\n }\n}\n\n\n### Test Example\njavascript\nconsole.log(jsonStringify({ x: 5, y: 6 })); // Output: {\"x\":5,\"y\":6}\nconsole.log(jsonStringify([1, \"false\", false])); // Output: [1,\"false\",false]\nconsole.log(jsonStringify({ x: [10, undefined, function(){}, Symbol('')] })); // Output: {\"x\":[10,null,null,null]}\n\n\nThis implementation is very basic and does not handle many complex cases such as Date objects, RegExp objects, BigInt, and circular references. In actual development, additional handling logic and optimizations should be added based on specific requirements.