<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>函数可以访问函数内部定义的变量:</p> <button type="button" onclick="myFunction()">点我</button> <p id="demo"></p> <script> function myFunction() { var a = 4; document.getElementById("demo").innerHTML = a * a; } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>函数可以访问定义在函数外的变量：</p> <button type="button" onclick="myFunction()">点我</button> <p id="demo"></p> <script> var a = 4; function myFunction() { document.getElementById("demo").innerHTML = a * a; } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>全局变量计数。</p> <button type="button" onclick="myFunction()">计数!</button> <p id="demo">0</p> <script> var counter = 0; function add() { return counter += 1; } function myFunction(){ document.getElementById("demo").innerHTML = add(); } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>局部变量计数。</p> <button type="button" onclick="myFunction()">计数!</button> <p id="demo">0</p> <script> function add() { var counter = 0; return counter += 1; } function myFunction(){ document.getElementById("demo").innerHTML = add(); } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>局部变量计数。</p> <p id="demo">0</p> <script> document.getElementById("demo").innerHTML = add(); function add() { var counter = 0; function plus() {counter += 1;} plus(); return counter; } </script> </body> </html>
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>菜鸟教程(runoob.com)</title> </head> <body> <p>局部变量计数。</p> <button type="button" onclick="myFunction()">计数!</button> <p id="demo">0</p> <script> var add = (function () { var counter = 0; return function () {return counter += 1;} })(); function myFunction(){ document.getElementById("demo").innerHTML = add(); } </script> </body> </html>
