Debug in JavaScrip

blog/Debug in JavaScrip.md

@@ -0,0 +1,86 @@
+---
+date: 2024-08-01
+tags: [JavaScript, Debug]
+---
+
+# Debug in JavaScrip
+
+<!--truncate-->
+
+## `debugger`
+
+In browser, `debugger` can trigger breakpoint
+
+```js
+debugger;
+```
+
+## Debug native function
+
+```js
+function debug(fn) {
+    return function () {
+        debugger;
+        return fn.apply(this, arguments);
+    };
+}
+```
+
+To debug `"string".at()`
+
+```js
+String.prototype.at = debug(String.prototype.at);
+```
+
+To debug `console.log()`
+
+```js
+console.log = debug(console.log);
+```
+
+## Inject function
+
+```js
+function inject(to, fn) {
+    return function () {
+        fn.apply(this, arguments);
+        return to.apply(this, arguments);
+    };
+}
+```
+
+To log the call stack and arguments when `"string".replace()` is called
+
+```js
+String.prototype.replace = inject(
+    String.prototype.replace,
+    function () {
+        console.trace();
+        console.log(arguments);
+    }
+);
+
+"abc".replace("a", "s");
+```
+
+## Call stack trace
+
+Get the call stack
+
+```js
+new Error().stack
+```
+
+Print the call stack
+
+```js
+console.trace();
+
+console.trace("message");
+```
+
+## Debug in node.js
+
+```cli
+node --inspect server.js
+```