node . js dnspromses . resolvetxt()方法

原文:https://www . geesforgeks . org/node-js-dnspromses-resolve text-method/

方法是 Promises 对象 dns 模块的内置应用编程接口，用于使用 DNS 协议解析指定主机名的 Txt 或文本查询记录。

语法:

dnsPromises.resolveTxt( hostname )

参数:该方法有一个参数如上所述，描述如下:

• Hostname: This parameter specifies a string that represents the hostname to be resolved.

返回值:这个方法返回错误，地址。

下面的例子说明了方法在 Node.js 中的使用:

例 1:

// Node.js program to demonstrate the   
// dnsPromises.resolveTxt() method

// Accessing promises object from dns module
const dns = require('dns');
const dnsPromises = dns.promises;

// Calling dnsPromises.resolveTxt() method 
dnsPromises.resolveTxt('google.com').then((res) => {
    console.log("for google : ");
    console.log(res);
});

输出:

for google :
[ [ 'docusign=1b0a6754-49b1-4db5-8540-d2c12664b289' ],
  [ 'docusign=05958488-4752-4ef2-95eb-aa7ba8a3bd0e' ],
  [ 'facebook-domain-verification=22rm551cu4k0ab0bxsw536tlds4h95' ],
  [ 'globalsign-smime-dv=CDYX+XFHUw2wml6/Gb8+59BsH31KzUr6c1l2BPvqKX8=' ],
  [ 'v=spf1 include:_spf.google.com ~all' ] 
]

例 2:

// Node.js program to demonstrate the   
// dnsPromises.resolveTxt() method

// Accessing promises object from dns module
const dns = require('dns');
const dnsPromises = dns.promises;

// Calling dnsPromises.resolveTxt() method 
// asynchronously 
(async function() {

    // Records from resolveTxt function
    const records = await dnsPromises.resolveTxt(
                    'geeksforgeeks.org');

    // Printing  records
    console.log("from async: ");
    console.log(records);   
})();

输出:

from async:
[ [ 'v=spf1 include:amazonses.com include:_spf.google.com -all' ],
  [ 'fob1m1abcdp777bf2ncvnjm08n' ]
]

注意:以上程序使用node index.js命令编译运行。

参考:https://nodejs . org/API/DNS . html # DNS _ dnsprymes _ resolve txt _ hostname

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