Three output methods of JavaScript: 1. Pop up a warning box for output, the syntax is "alert("output information")"; 2. Console output, the syntax is "console.log("output information")" ;3. Browser visible area output, syntax "document.write("output information")".
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
1. alert(year) pops up a warning box
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> // 定义一个变量 存储一个人的年龄 var year = 23; alert(year) </script> </body> </html>
2. console.log() console output
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> // 定义一个变量 存储一个人的年龄 var year = 23; console.log(year); </script> </body> </html>
Console after pressing F12
3. Output document.write() to the browser’s visible area
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> // 定义一个变量 存储一个人的年龄 var year = 23; document.write(year) </script> </body> </html>
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