EncodeURI. URLs use special syntax—for example they encode a hash sign as a character sequence "%23." Spaces can also be encoded.
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);
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
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.
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.replace
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