Add JS equality blog

blog_posts/javascript-equality.md

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+---
+title: What is the difference between JavaScript's equality operators?
+type: question
+tags: javascript,type,comparison
+authors: chalarangelo
+cover: blog_images/js-equality.jpg
+excerpt: Learn all you need to know about the differences between JavaScript's double equals and triple equals operators.
+---
+
+JavaScript provides two equality operators used for comparisons:
+
+- The double equals (`==`), also known as the loose equality operator
+- The triple equals (`===`), also known as the strict equality operator
+
+The key difference between the two is that the triple equals (`===`) operator compares both type and value, whereas the double equals (`==`) operator uses type coercion so that both operands are of the same type, then compares only the resulting values.
+
+Here are some examples to clear up any confusion:
+
+```js
+const num = 0;
+const str = '0';
+const obj = new String(0);
+const bool = false;
+const undef = undefined;
+const nil = null;
+
+console.dir([
+  num == str,     // 0 == 0, true
+  num == bool,    // 0 == 0, true
+  str == obj,     // '0' == '0', true
+  obj == num,     // 0 == 0, true
+  bool == str,    // 0 == 0, true
+  bool == obj,    // 0 == 0, true
+  bool == nil,    // false
+  undef == nil,   // true
+  undef == bool,  // false
+]);
+
+console.dir([
+  num === str,     // types don't match, false
+  num === bool,    // types don't match, false
+  str === obj,     // types don't match, false
+  obj === num,     // types don't match, false
+  bool === str,    // types don't match, false
+  bool === obj,    // types don't match, false
+  bool === nil,    // types don't match, false
+  undef === nil,   // types don't match, false
+  undef === bool,  // types don't match, false
+]);
+```
+
+As you can see from the examples above, using the triple equals (`===`) operator is far more predictable and intuitive than the double equals (`==`) operator. Therefore, we recommend you use the triple equals (`===`) operator for most cases, unless you are entirely certain you want type coercion to be applied to the comparison's operands.
+
+**Image credit:** [Evi Radauscher](https://unsplash.com/@eviradauscher?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText) on [Unsplash](https://unsplash.com/s/photos/code?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText)