Query String Parameters & Methods in NodeJS.pptx

Query strings and parameters in processing url

1. Query String Parameters & Methods in NodeJS

2. What is Query String in NodeJS There are ways to deal with query strings thanks to the  Node.js Query String.  It can transform a query string into a JSON object and the other way around. Now, there are methods for parsing and formatting URL query strings available in the Node.js query string module. The following command will access the query string module: const querystring = require(‘ querystring ’);

3. In NodeJS the following are the six Query String Parameters listed below. decode() encode() escape(str) parse(str[, sep [, eq [, options]]]) stringify ( obj [, sep [, eq [, options]]]) unescape (str)

4. Query String methods in NodeJS with Description querystring.parse () Method in NodeJS The URL query string is parsed into an object with a key-value pair using the querystring.parse () function. We cannot utilize Object methods like obj.toString or obj.hasOwnProperty since the object we receive is not a JavaScript object (). The syntax for the method is below. querystring.parse ( str[, sep [, eq[, options]]]) )

5. The syntax for the method is below. querystring.parse ( str[, sep [, eq[, options]]]) ) As seen from the above syntax this method accepts four parameters, which are described below. str:  This is the only required string field and it specifies in the query string that has to be parsed. sep :  If provided, it is an optional string parameter that specifies the substring that will be used to separate the query string’s key and value pairs. The default value used is “&”. eq:  It is an optional string field that is used in the query string to separate the keys from the values. The default value used is “=”. options:  It is an optional object field that is used to modify the behavior of the method. It can have the following parameters: decodeURIComponent :  It is a function that would be used to provide the query string’s encoding format. The default setting is querystring.unescape (), about which we will learn later. maxKeys :  This value indicates how many keys in total should be processed. Any number of keys can be parsed if the value is set to “0,” which eliminates any counting restrictions. The default setting is “1000.”

6. The syntax for the method is below. querystring . stringify ( obj[, sep [, eq[, options]]]) ) The method accepts four parameters, which are specified below, as can be seen from the syntax above. obj:  The sole object field that is necessary defines the object that has to be serialized. sep :  It is a string field that is optional and, if provided, provides the substring that will be used to separate the key and value pairs in the query string. “&” is the default value, which is typically used. eq:  The substring used to separate the query string’s keys and values are specified in this optional string parameter. In most cases, the default value is “=”. options:  It is an optional object field that is used to change how the method behaves. It can have the following parameters: decodeURIComponent :  It is a function that would be utilized to specify the query string’s encoding format. The default value is querystring.escape (), about which we will learn later.

7. querystring.decode () Method in NodeJS A simple alias for the querystring.parse () function is querystring.decode (). We can use it in our parsing example. Add the following code to the querystring.js file we previously established. // Import the querystring module const querystring = require(“ querystring ”); // Specify this URL query string to be parsed let urlQueryString = “name= nabendu&units = kgs&units = pounds&login =false”; // Use the parse() method on the string let parsedObj = querystring.decode ( urlQueryString ); console.log(“Parsed Query 1:”, parsedObj ); Run the node querystring.js command from a terminal, as you did before. The result will be identical to that of the querystring.parse () function. Parsed Query 1: [Object: null prototype] { name: ‘ bhanu ’, units: [ ‘kgs’, ‘pounds’ ], login: ‘false’ }

8. querystring .stringify () Method in NodeJS A supplied object that has a key-value pair can be utilized to create a query string using the querystring.stringify () method. When compared to querystring.parse (), it is the exact opposite. The string, integer, and Boolean values for the key can all be converted using it. An array of strings, numbers, or Boolean values can also be used as values. Serialization is the process of converting an object to a query string. Unless we indicate an alternative encoding format, the most recent UTF-8 encoding format is taken into account. But since UTF-8 encoding is the industry standard and includes all international characters,

9. querystring.encode () Method in NodeJS A simple alias for the querystring.stringify () technique is querystring.encode (). We can use it in our stringify example. Add the following code to the querystring.js file we previously established. // Import the querystring module const querystring = require(“ querystring ”); // Name the object that required serialisation. let obj = { name: “ nabendu ”, access: true, role: [“developer”, “architect”, “manager”], }; // Use the stringify () method on the object let queryString = querystring.encode ( obj ); console.log(“Query String 1:”, queryString ); Run the terminal command node querystring.js like we did earlier. And the results will match those of the querystring.stringify () function. Query String 1: name= nabendu&access = true&role = developer&role = architect&role =manager

10. querystring.escape (str) Method in NodeJS The querystring.escape () function is typically only utilised by the querystring.stringify () method. f.querystring.unescape (str) Method The querystring.unescape () method is often only utilised by the querystring.parse () method..