contents(js): add explanation to double equal vs triple equal

questions/what-is-the-difference-between-double-equal-and-triple-equal/en-US.mdx

@@ -39,6 +39,64 @@ However, when using `==`, unintuitive results can happen:
 
 As a general rule of thumb, never use the `==` operator, except for convenience when comparing against `null` or `undefined`, where `a == null` will return `true` if `a` is `null` or `undefined`.
 
+
+Let's break down each of the comparisons:
+
+1️⃣ null == undefined → true
+Why?
+null and undefined are loosely equal (==) but not strictly equal (===).
+JavaScript defines a special rule:
+null == undefined; // true
+
+However:
+null === undefined; // false
+(because === checks both type and value).
+
+console.log(null == undefined); // true
+console.log(null === undefined); // false
+
+📌 Key Rule:
+null and undefined are only equal to each other but not to anything else.
+
+2️⃣ [] == false → true
+Why?
+[] (empty array) is truthy, but when compared with false, it gets coerced into a primitive value.
+JavaScript converts false to a number (0).
+Then, it converts [] to a string ('') → and an empty string is also 0 when converted to a number.
+So, the comparison becomes:
+
+Number([]) == Number(false);  
+0 == 0; // true
+
+console.log([] == false); // true
+console.log([] == 0); // true
+console.log(Number([])); // 0
+📌 Key Rule:
+An empty array [] converts to 0 in numeric comparison.
+
+3️⃣ '' == false → true
+Why?
+JavaScript converts false to 0.
+An empty string '' also converts to 0 in numeric comparisons.
+
+So the comparison becomes:
+Number('') == Number(false);
+0 == 0; // true
+Example
+console.log('' == false); // true
+console.log('' == 0); // true
+console.log(Number('')); // 0
+📌 Key Rule:
+An empty string '' converts to 0 in numeric comparison.
+
+🔹 Summary of Type Coercion Rules
+null == undefined	Special case in JS	✅ true
+[] == false ------ [] → '' → 0, false → 0, so 0 == 0	✅ true
+'' == false	------ '' → 0, false → 0, so 0 == 0	✅ true
+📌 ⚠️ Important Note:
+These type coercion behaviors can be confusing, which is why it's recommended to use === (strict equality) to avoid unexpected results.
+
+
 ```js
 var a = null;
 console.log(a == null); // true