Add Conditionally Include Pairs In An Object as a javascript til

javascript/conditionally-include-pairs-in-an-object.md

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+# Conditionally Include Pairs In An Object
+
+You can add key-value pairs to an object using the ES6 spread operator:
+
+```javascript
+> { one: 1, ...{ hello: "world" } }
+{ one: 1, hello: "world" }
+```
+
+By combining the spread operator with some boolean logic, you can conditionally
+add key-value pairs to an object:
+
+```javascript
+> {
+    one: 1,
+    ...(isArriving && { hello: "world" }),
+  }
+```
+
+Depending on the value of `isArriving`:
+
+```javascript
+// isArriving === true
+{ one: 1, hello: "world" }
+```
+
+or
+
+```javascript
+// isArriving === false
+{ one: 1 }
+```
+
+This is useful for dynamically building up some configuration object or data
+payload.