Differences

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--- java-script:object-to-string-and-back [2023/08/11 09:34] – created odefta
+++ java-script:object-to-string-and-back [2023/08/11 09:59] (current) – [Notes] odefta
@@ Line 21: / Line 21: @@
 ===== Object to String =====
-  - **JSON.stringify**: This method converts a JavaScript object into a JSON string.
+  - **JSON.stringify**: This method converts a JavaScript object into a JSON string. <code javascript>const obj = { name: 'John', age: 30 };
-<code javascript>const obj = { name: 'John', age: 30 };
 const str = JSON.stringify(obj); // '{"name":"John","age":30}'
 </code>
-  - **toString Method**: If the object has a custom toString method, you can call it to get a string representation.
+  - **toString Method**: If the object has a custom toString method, you can call it to get a string representation. <code javascript>
-<code javascript>
 const obj = {
   name: 'John',
   age: 30,
   toString: function() {
-    return `Name: ${this.name}, Age: ${this.age}`;
+    return `{"name":"${this.name}","age":${this.age}}`;
   }
 };
-const str = obj.toString(); // 'Name: John, Age: 30'
+const str = obj.toString(); // '{"name":"John","age":30}'
 </code>
+===== String to Object =====
+**JSON.parse**: This method parses a JSON string and constructs the JavaScript value or object described by the string.
+<code javascript>
+const str = '{"name":"John","age":30}';
+const obj = JSON.parse(str); // { name: 'John', age: 30 }
+</code>
+===== Notes =====
+<note>
+**JSON.stringify** will only include properties that have enumerable **string keys**. It will exclude properties with symbol keys, and it will also **skip** values that are **undefined, functions, or symbols**.
+</note>
+<note>
+**JSON.parse** expects a **valid JSON** string. If the string is not valid JSON, it will throw an error.
+</note>
+<note>
+If you're working with a more complex object structure that includes methods or other non-serializable values, you may need to implement custom serialization/deserialization logic.
+</note>
+<note tip>
+You can format the output of the **JSON.stringify** to be more easy to read or add transformation / filtering.
+Syntax:
+<code javascript>
+JSON.stringify(value, replacer, space)
+</code>
+  * **value**: The value to convert to a JSON string.
+  * **replacer**: Either a function that alters the behavior of the stringification process or an array of String and Number that serve as a whitelist for selecting/filtering the properties of the value object to be included in the JSON string. Passing **null** means that the entire object is included, without any changes.
+  * **space**: A String or Number object that's used to insert **white space** into the output JSON string for readability purposes.
+Example:
+<code javascript>
+const obj = {
+  name: 'John',
+  age: 30,
+  friends: ['Alice', 'Bob']
+};
+const jsonString = JSON.stringify(obj, null, 2);
+// 2 is the number of spaces for indentation
+</code>
+Output:
+<code javascript>
+{
+  "name": "John",
+  "age": 30,
+  "friends": [
+    "Alice",
+    "Bob"
+  ]
+}
+</code>
+To ski age from being included:
+<code javascript>
+const obj = { name: 'John', age: 30 };
+const filteredJSON = JSON.stringify(obj, ['name']);
+console.log(filteredJSON); // '{"name":"John"}'
+</code>
+</note>