Asynchronous String.prototype.replace()
npm install string-replace-async> A vesion of "string".replace() that knows how to wait
``
$ npm install string-replace-async
Note: If you're using pre-14 version of Node or your node codebase isn't converted to ES Modules yet, please use Version 2 specifically!
`
$ npm install string-replace-async@^2.0.0
`js
import replaceAsync from "string-replace-async";
await replaceAsync("#rebeccapurple", /#(\w+)/g, async (match, name) => {
let color = await getColorByName(name);
return "#" + color + " (" + name + ")";
});
`
Say you have a task of replacing color names with their respective hex codes.
`js`
let spec = "I want background to be #papayawhip and borders #rebeccapurple.";
// make it "I want background to be #FFEFD5 (papayawhip) and borders #663399 (rebeccapurple).";
Luckily, strings in JavaScript have this handy replace method built in, so you use it.
`js`
spec.replace(/#(\w+)/g, (match, name) => {
let color = getColorByName(name);
return "#" + color + " (" + name + ")";
});
Time passes, a new requirement emerges: now you have to query a database for custom colors. This is an async operation, so naturally you convert getColorByName into async function.
Turns out it has a cost: now all the code above should also be async. You try this:
`js`
await spec.replace(/#(\w+)/g, async (match, name) => {
let color = await getColorByName(name);
return "#" + color + " (" + name + ")";
});
Unfortunately, this code doesn't work as you expect. Built in menthod wasn't designed to work as async function.
This is where string-replace-async comes in:
`js`
await replaceAsync(spec, /#(\w+)/g, async (match, name) => {
let color = await getColorByName(name);
return "#" + color + " (" + name + ")";
});
Yay!
string-replace-async is nothing but direct String.prototype.replace replacement that awaits your function and returns a Promise for results.
API is
String.prototype.replace(), except the first argument is a string itself.
Runs replace and waits for it to resolve before replacing searchValue with results. If searchValue is a _global_ RegExp, replace will be called concurrently for every match.
#### string
Type: string
_Required_
An input string.
#### searchValue
Type: regexp, string
An expression to match substrings to replace.
#### replace
Type: function, string
A function that takes several arguments and returns a promise. Resolved value will be used as _replacement substring_.
Previously this module had an additional function seq() that ran replace functions one by one instead of all at once. We decided to remove it to narrow our scope. Here's a snippet that achieves the same effect:
`js
let sequence = Promise.resolve();
let seq = (fn) => (...args) => (sequence = sequence.then(() => fn(...args)));
await replaceAsync(
"#rebeccapurple, #papayawhip",
/#(\w+)/g,
seq(async (match, name) => {
let color = await getColorByName(name);
return "#" + color + " (" + name + ")";
})
);
``
MIT © Dmitrii Sobolev