node.js uses the require() function to load modules_node.js

Detailed explanations can be written in the comments, so I won’t go into details here. Friends, please read them in detail yourself. Don’t take the comments as nothing.

Copy code The code is as follows:

/*In node, you can use the require() function to load modules.
* The require function uses a parameter, and the parameter value can be the file name of the module with a full path, or it can be the module name. When using the module provided in node, you only need to specify the module name in the require function.
* */
//Create a page 2.js; the code is as follows
var name="Dr. Sisi";
exports.name=name;
//Create a page 1.js; the code is as follows
var two=require("./2.js");
console.log(two.name);
//Output result: Dr. Sisi
/*
* All script files in node are a module file, so 1.js is also a module file, and since the file is directly run through the node command in the command line window, the module file is defined in node For the main module of the application
* You can use the following method to detect whether the current module is the main module
* */
if(module===require.main){
console.log("The current module is the main module");
}
//Output result: The current module is the main module
//2.js code
var name="Dr. Sisi";
console.log(name);
exports.name=name;
//1.js code:
var two=require("./2.js");
var two=require("./2.js");
//Although it is referenced twice, the output of console.log(name) is only executed once.
/*require.resolve(str)
* In node, you can use this function to query the file name of a module file with a complete absolute path.
* */
var url=require.resolve("./2");
console.log(url);
//Output result:E:nodegys2.js
/*require.cache
* In node, this attribute represents the cache area of ​​all loaded modules.
* */
var two=require("./2.js");
var cache=require.cache;
console.log(cache);
/*Output result:
* { 'E:\node\gys\1.js':
{ id: '.',
exports: {},
parent: null,
filename: 'E:\node\gys\1.js',
loaded: false,
children: [ [Object] ],
paths:
[ 'E:\node\gys\node_modules',
'E:\node\node_modules',
'E:\node_modules' ] },
'E:\node\gys\2.js':
{ id: 'E:\node\gys\2.js',
exports: { name: 'Dr. Sisi' },
parent:
{ id: '.',
exports: {},
parent: null,
filename: 'E:\node\gys\1.js',
loaded: false,
children: [Object],
paths: [Object] },
filename: 'E:\node\gys\2.js',
loaded: true,
children: [],
paths:
[ 'E:\node\gys\node_modules',
'E:\node\node_modules',
'E:\node_modules' ] } }
* */
//2.js code
var name="Dr. Sisi";
console.log(name);
//1.js code
//When the delete keyword is used to delete a module object cached in the cache area, the code in the module will be re-run the next time the module is loaded. Usage code:
var two=require("./2.js");
var two1=require("./2.js");
console.log("Before deletion")
delete require.cache[require.resolve("./2.js")];
console.log("After deletion");
var two2=require("./2.js");
/*
* Output result:
* Dr. Sisi
* Before deletion
*After deletion
* Dr. Sisi
* */

Have you guys understood the usage of the require() function in node? This article is based on my own understanding. If there are any omissions, please correct me.