Node. JS Series notes 4-(not updated regularly)

• node. JS Global Object
  • Special objects in JavaScript: Global objects, Universal object
  • It and all its properties can be accessed from anywhere in the program
  • In browser JavaScript, typically window is a global object, and node. JS is global, and all global variables (except global itself) are properties of the global object
  • ECMAScript definition, global variables include
    • Variables defined at the outermost layer
    • Properties of global objects
    • Implicitly defined variables (no direct assignment defined)
  • When defining a global variable, this variable becomes a property of the global object and vice versa
  • It is not possible to define variables at the outermost layer in node. js because all user code belongs to the current module and the module itself is not at the outermost
  • Note It is best to always use Var to define variables to avoid introducing global variables, which pollute namespaces and increase the risk of code coupling
• __filename
  • Console.log (__filename);
  • Output the file name of the currently executing script, output absolute path
  • If the module file path is output in the module
• __dirname
  • Console.log (__dirname);
  • The directory where the output execution script resides
• SetTimeout (CB, MS)
  • The global function, which executes the specified function CB after the specified number of milliseconds, executes only once
  • Note that the program does not stop at this statement, but will continue
• Cleartimeout (t)
  • Used to stop a timer that was previously created by SetTimeout ()

  • 1 var t = setTimeout (Printhello, +); 2 cleartimeout (t);

• Console
  • Console is used to provide console standard output, which is a debugging tool provided by IE's JScript engine, and later becomes the de facto standard of the browser.
  • node. JS uses this standard to stderr output characters to standard output stream stdout and standard error streams
  • Console method
    • Links: http://www.runoob.com/nodejs/nodejs-global-object.html
• Process
  • Process is a global variable, that is, the properties of the global object
  • An object that describes the state of the current node. JS process and provides a simple interface to communicate with the operating system
  • Event: Exit/beforeexit/uncaughtexcepiton/signal
  • Exit Status:
  • Property: Stdout/stderr/stdin/argv/execpath/env/exitcode/version/pid/platform
  • Method Reference Manual:
  • Links: http://www.runoob.com/nodejs/nodejs-global-object.html

Node. JS Series notes 4-(not updated regularly)