EncodeURI. On web sites, URLs use special syntax—for example they encode a hash sign as a character sequence "%23." Spaces can also be encoded.
In a Node.js program, we want to encode and decode URIs when we interact with the browser's location. This does not need to be done manually (except in special cases).
EncodeURIComponent. Suppose our app creates a "component" of a URL, not an entire URL. Symbols such as the hash and ampersand should be encoded, not left in their original condition.
Tip With encodeURIComponent, we convert valid URL characters to their encoded representation for use in a component (not a full URL).
var part = "c# bird & fish";
// The encodeURIComponent method will encode hash signs.
var result = encodeURIComponent(part);
console.log("ENCODE BEORE: " + part);
console.log("ENCODE AFTER: " + result);ENCODE BEORE: c# bird & fish
ENCODE AFTER: c%23%20bird%20%26%20fish
EncodeURI example. This method is like encodeComponentURI but it does not encode certain chars like the hash symbol. These are left alone and considered part of the URL structure.
var part = "f# example";
// The encodeURIComponent method will not encode some things.// ... If you want those things encoded, use encodeURIComponent.
var result = encodeURI(part);
console.log("ENCODEURI: " + result);ENCODEURI: f#%20example
DecodeURI. This method does the opposite of encodeURI—it transforms an encoded URL back into a normal string format. We can use its decodeURIComponent counterpart.
var part = "c%23%20example";
// Use decodeURI and decodeURIComponent methods.
var result1 = decodeURI(part);
var result2 = decodeURIComponent(part);
console.log("DECODEURI: " + result1);
console.log("DECODEURICOMPONENT: " + result2);DECODEURI: c%23 example
DECODEURICOMPONENT: c# example
Performance note. In my testing, replace() calls that replace characters globally were slower than encodeURIComponent. Three replace calls were about 3 times slower than encodeURIComponent.
So When possible, use encodeURIComponent to fix encodings—it is faster and simpler to use.
Summary. It is tempting to write "replace" calls for URLs to fix their characters. This is a bad idea. With specialized methods like encodeURI we have a faster and clearer solution.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Dec 13, 2023 (edit).