Quartz sync: May 6, 2024, 10:40 PM

content/20201104102343-javascript_regexp_replace_method.md

@@ -0,0 +1,46 @@
+---
+id: 11d0fefd-c11e-400b-80fd-ba40e94b2a47
+title: JavaScript RegExp Replace Method
+---
+
+replace[^1] is a nice way to use regexps to replace text:
+
+``` javascript
+console.log("papa".replace("p", "m"));
+console.log("Borobudur".replace(/[ou]/, "a"));
+console.log("Borobudur".replace(/[ou]/g, "a"));
+```
+
+You can also use awk like syntax to switch things around:
+
+``` javascript
+console.log(
+  "Liskov, Barbara\nMcCarthy, John\nWadler, Philip"
+    .replace(/(\w+), (\w+)/g, "$2 $1"));
+```
+
+You can even pass a function to replace:
+
+``` javascript
+let s = "the cia and fbi";
+console.log(s.replace(/\b(fbi|cia)\b/g,
+            str => str.toUpperCase()));
+```
+
+``` javascript
+let stock = "1 lemon, 2 cabbages, and 101 eggs";
+function minusOne(match, amount, unit) {
+  amount = Number(amount) - 1;
+  if (amount == 1) { // only one left, remove the 's'
+    unit = unit.slice(0, unit.length - 1);
+  } else if (amount == 0) {
+    amount = "no";
+  }
+  return amount + " " + unit;
+}
+console.log(stock.replace(/(\d+) (\w+)/g, minusOne));
+```
+
+# Footnotes
+
+[^1]: <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/replace>