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Node.js URLsearchParams API

Last Updated : 10 Jul, 2020
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Node.js is an open-source project widely used for the development of dynamic web applications. The URLSearchParams API in Node.js allows read and write operations on the URL query. The URLSearchParams class is a global object and used with one of the four following constructors. Constructors:
  1. new URLSearchParams(): No argument constructor instantiates a new empty URLSearchParams object.
  2. new URLSearchParams(string): Accepts a string as an argument to instantiate a new URLSearchParams object. javascript 
    var params = new URLSearchParams('user=abc&q=xyz');
console.log(params.get('user'));
console.log(params.get('q'));
    Output: 
    abc
xyz
  3. new URLSearchParams(obj): Accepts an object with a collection of key-value pairs to instantiate a new URLSearchParams object. The key-value pair of obj are always coerced to strings. Duplicate keys are not allowed. javascript 
    const params = new URLSearchParams({
  user: 'ana',
  course: ['math', 'chem', 'phys']
});
console.log(params.toString());
    Output: 
    user=ana&course=math%2Cchem%2Cphys
  4. new URLSearchParams(iterable): Accepts an iterable object having a collection of key-value pairs to instantiate a new URLSearchParams object. Iterable can be any iterable object. Since URLSearchParams is iterable, an iterable object can be another URLSearchParams, where the constructor will create a clone of the provided URLSearchParams. Duplicate keys are allowed. JavaScript 
    // Using a Map object as it is iterable
const map = new Map();
map.set('West Bengal', 'Kolkata');
map.set('Karnataka', 'Bengaluru');
params = new URLSearchParams(map);
console.log(params.toString());
    Output: 
    West+Bengal=Kolkata&Karnataka=Bengaluru
Accessing the URL query:
  • urlSearchParams.get(name): Returns the value of the first name-value pair that matches with the argument passed. If no such pair exists, null is returned. javascript 
    const myURL = new URL(
  'https://example.org/?abc=123&abc=526');

console.log(myURL.searchParams.get('abc'));
    Output: 
    123
  • urlSearchParams.getAll(name): Returns all the value of the name-value pair that matches with the argument passed. If no such pair exists, null is returned. javascript 
    const myURL = new URL(
  'https://example.org/?abc=123&abc=526');
console.log(myURL.searchParams.getAll('abc'));
    Output: 
    [ '123', '526' ]
  • urlSearchParams.has(name): Returns true if the argument passed matches with any existing name of the name-value pair else returns false. javascript 
    const myURL = new URL(
  'https://example.org/?abc=123&xyz=526');
console.log(myURL.searchParams.has('abc'));
console.log(myURL.searchParams.has('pqr'));
    Output: 
    true
false
Manipulating the URL query:
  • urlSearchParams.set(name, value): Sets the value in the URLSearchParams object associated with name to the specified value. If more than one name-value pairs exists, whose names are same as the 'name' argument, then the only value of first matching pair is changed, rest all are removed. javascript 
    const params = new URLSearchParams(
    'abc=123&xyz=526&abc=258');
console.log(params.toString());
params.set('abc', 'opq');
console.log(params.toString());
    Output: 
    abc=123&xyz=526&abc=258
abc=opq&xyz=526
  • urlSearchParams.append(name, value): Appends a new name-value pair to the existing URLSearchParams query. javascript 
    const params = new URLSearchParams('xyz=123');
params.append('foo', '789');
params.append('xyz', 'zoo');
params.append('foo', 'def');
console.log(params.toString());
    Output: 
    xyz=123&foo=789&xyz=zoo&foo=def
  • urlSearchParams.delete(name): Removes all name-value pairs whose name is same as 'name' argument. javascript 
    const params = new URLSearchParams(
  'xyz=123&foo=789&xyz=zoo&foo=def');
console.log(params.toString());
params.delete('foo');
console.log(params.toString());
    Output: 
    xyz=123&foo=789&xyz=zoo&foo=def
xyz=123&xyz=zoo
  • urlSearchParams.sort(): Sorts the existing name-value pairs in-place by their names using a stable sorting algorithm. javascript 
    const params = new URLSearchParams(
  'query=node&type=search&abc=programs');
params.sort();
console.log(params.toString());
    Output: 
    abc=programs&query=node&type=search
  • urlSearchParams.toString(): Returns the URL search parameters as a string, with characters percent-encoded wherever necessary. javascript 
    const params = new URLSearchParams(
  'query=node&type=search&passwd[]=3456');
console.log(params.toString());
    Output: 
    query=node&type=search&passwd%5B%5D=3456
Iterating the URL query:
  • urlSearchParams.entries(): Returns an iterator over the entry set of the param object. javascript 
    const params = new URLSearchParams(
    'query=node&type=search&passwd=3456');
for(var pair of params.entries()) {
   console.log(pair[0]+ '-->'+ pair[1]); 
}
    Output: 
    query-->node
type-->search
passwd-->3456
  • urlSearchParams.keys(): Returns an iterator over the key set of the param object. javascript 
    const params = new URLSearchParams(
    'query=node&type=search&passwd=3456');
for(var key of params.keys()) {
   console.log(key); 
}
    Output: 
    query
type
passwd
  • urlSearchParams.values(): Returns an iterator over the value set of the param object. javascript 
    const params = new URLSearchParams(
    'query=node&type=search&passwd=3456');
for(var value of params.values()) {
   console.log(value); 
}
    Output: 
    node
search
3456
  • urlSearchParams.forEach(fn[, arg]): fn is a function invoked for each name-value pair in the query and arg is an object to be used when 'fn' is called. It iterates over each name-value pair in the query and invokes the function. javascript 
    const myURL = new URL(
  'https://example.com/?a=b&c=d&d=z');
myURL.searchParams.forEach(
  (value, name, searchParams) => {
console.log(name, value, 
  myURL.searchParams === searchParams);
});
    Output: 
    a b true
c d true
d z true
  • urlSearchParams[Symbol.iterator](): javascript 
    const params=new URLSearchParams(
    'firstname=john&lastname=beck&gender=male');
for (const [name, value] of params) {
  console.log(name, value);
}
    Output: 
    firstname john
lastname beck
gender male

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