Encode / decode URLs

You can do all the URL encoding you want with the net/url module. It doesn't break out the individual encoding functions for the parts of the URL, you have to let it construct the whole URL. Having had a squint at the source code I think it does a very good and standards compliant job.

Here is an example (playground link)

package main

import (
    "fmt"
    "net/url"
)

func main() {

    Url, err := url.Parse("http://www.example.com")
    if err != nil {
        panic("boom")
    }

    Url.Path += "/some/path/or/other_with_funny_characters?_or_not/"
    parameters := url.Values{}
    parameters.Add("hello", "42")
    parameters.Add("hello", "54")
    parameters.Add("vegetable", "potato")
    Url.RawQuery = parameters.Encode()

    fmt.Printf("Encoded URL is %q\n", Url.String())
}

Which prints-

Encoded URL is "http://www.example.com/some/path/or/other_with_funny_characters%3F_or_not/?vegetable=potato&hello=42&hello=54"

From MDN on encodeURIComponent:

encodeURIComponent escapes all characters except the following: alphabetic, decimal digits, '-', '_', '.', '!', '~', '*', ''', '(', ')'

From Go's implementation of url.QueryEscape (specifically, the shouldEscape private function), escapes all characters except the following: alphabetic, decimal digits, '-', '_', '.', '~'.

Unlike Javascript, Go's QueryEscape() will escape '!', '*', ''', '(', ')'. Basically, Go's version is strictly RFC-3986 compliant. Javascript's is looser. Again from MDN:

If one wishes to be more stringent in adhering to RFC 3986 (which reserves !, ', (, ), and *), even though these characters have no formalized URI delimiting uses, the following can be safely used:

function fixedEncodeURIComponent (str) {
  return encodeURIComponent(str).replace(/[!'()]/g, escape).replace(/\*/g, "%2A");
}