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Get number of open orders for a symbol using Binance's Node.js API

I am using Binance's Node.js API. It says regarding "Get open orders for a symbol", I should do:
binance.openOrders("ETHBTC", (error, openOrders, symbol) => {
console.info("openOrders("+symbol+")", openOrders);
});
To print out number of open orders, I do:
binance.openOrders("ETHBTC", (error, openOrders, symbol) => {
console.info(openOrders.length);
});
which works and the number gets printed out. However, I would need this result to be stored in a variable which can be used later by other functions. Building on SO's Javascript chat room, I do:
let OO =
(async() => {
const openOrders = await binance.openOrders(false);
return openOrders.length
})()
console.log(OO)
This however prints
Promise { <pending> }
only.
I have seen several other questions discussing Promise { <pending> } issue but I haven't been able to implement their solutions to this specific case.
How could I get number of open orders into a variable accessible by other functions?

You'll need to use either completely async approach or use callbacks.
The last block in your question shows exactly what this answer explains. Javascript doesn't wait for Promise to resolve/reject in a synchronous context. So your "async" block returned the unresolved Promise and the rest of your (synchronous) code didn't wait for it to resolve.
Example of using async functions
const getOpenOrdersCount = async () => {
const openOrders = await binance.openOrders("ETHBTC");
return openOrders.length;
};
const run = async () => {
const openOrdersCount = await getOpenOrdersCount();
console.log(openOrdersCount);
}
Note: You can use await only within async functions.
Example of using callbacks is your code. They are useful in a small scope, but in bigger scope they get messy and turn into a callback hell. So I wouldn't recommend using callbacks in a bigger scope.
binance.openOrders("ETHBTC", (error, openOrders, symbol) => {
console.info(openOrders.length);
// here goes rest of your code that needs to use the `openOrders` variable
});

js - why is await not throwing error when used outside function [duplicate]

I have been going over async/await and after going over several articles, I decided to test things myself. However, I can't seem to wrap my head around why this does not work:
async function main() {
var value = await Promise.resolve('Hey there');
console.log('inside: ' + value);
return value;
}
var text = main();
console.log('outside: ' + text);
The console outputs the following (node v8.6.0) :
> outside: [object Promise]
> inside: Hey there
Why does the log message inside the function execute afterwards? I thought the reason async/await was created was in order to perform synchronous execution using asynchronous tasks.
Is there a way could I use the value returned inside the function without using a .then() after main()?

I can't seem to wrap my head around why this does not work.
Because main returns a promise; all async functions do.
At the top level, you must either:
Use top-level await (proposal, MDN; ES2022, broadly supported in modern environments) that allows top-level use of await in a module.
or
Use a top-level async function that never rejects (unless you want "unhandled rejection" errors).
or
Use then and catch.
#1 top-level await in a module
You can use await at the top-level of a module. Your module won't finish loading until the promise you await settles (meaning any module waiting for your module to load won't finish loading until the promise settles). If the promise is rejected, your module will fail to load. Typically, top-level await is used in situations where your module won't be able to do its work until the promise is settled and won't be able to do it at all unless the promise is fulfilled, so that's fine:
const text = await main();
console.log(text);
If your module can continue to work even if the promise is rejected, you could wrap the top-level await in a try/catch:
// In a module, once the top-level `await` proposal lands
try {
const text = await main();
console.log(text);
} catch (e) {
// Deal with the fact the chain failed
}
// `text` is not available here
when a module using top-level await is evaluated, it returns a promise to the module loader (like an async function does), which waits until that promise is settled before evaluating the bodies of any modules that depend on it.
You can't use await at the top level of a non-module script, only in modules.
#2 - Top-level async function that never rejects
(async () => {
try {
const text = await main();
console.log(text);
} catch (e) {
// Deal with the fact the chain failed
}
// `text` is not available here
})();
// `text` is not available here, either, and code here is reached before the promise settles
// and before the code after `await` in the main function above runs
Notice the catch; you must handle promise rejections / async exceptions, since nothing else is going to; you have no caller to pass them on to (unlike with #1 above, where your "caller" is the module loader). If you prefer, you could do that on the result of calling it via the catch function (rather than try/catch syntax):
(async () => {
const text = await main();
console.log(text);
})().catch(e => {
// Deal with the fact the chain failed
});
// `text` is not available here, and code here is reached before the promise settles
// and before the code after `await` in the main function above runs
...which is a bit more concise, though it somewhat mixes models (async/await and explicit promise callbacks), which I'd normally otherwise advise not to.
Or, of course, don't handle errors and just allow the "unhandled rejection" error.
#3 - then and catch
main()
.then(text => {
console.log(text);
})
.catch(err => {
// Deal with the fact the chain failed
});
// `text` is not available here, and code here is reached before the promise settles
// and the handlers above run
The catch handler will be called if errors occur in the chain or in your then handler. (Be sure your catch handler doesn't throw errors, as nothing is registered to handle them.)
Or both arguments to then:
main().then(
text => {
console.log(text);
},
err => {
// Deal with the fact the chain failed
}
);
// `text` is not available here, and code here is reached before the promise settles
// and the handlers above run
Again notice we're registering a rejection handler. But in this form, be sure that neither of your then callbacks throws any errors, since nothing is registered to handle them.

2021 answer: you can now use top level await in the current stable version of node
Most of the answers above are a little out of date or very verbose, so here's a quick example for node 14 onwards.
Make a file called runme.mjs:
import * as util from "util";
import { exec as lameExec } from "child_process";
const exec = util.promisify(lameExec);
const log = console.log.bind(console);
// Top level await works now
const { stdout, stderr } = await exec("ls -la");
log("Output:\n", stdout);
log("\n\nErrors:\n", stderr);
Run node runme.mjs
Output:
total 20
drwxr-xr-x 2 mike mike 4096 Aug 12 12:05 .
drwxr-xr-x 30 mike mike 4096 Aug 12 11:05 ..
-rw-r--r-- 1 mike mike 130 Aug 12 12:01 file.json
-rw-r--r-- 1 mike mike 770 Aug 12 12:12 runme.mjs
Errors:

Top-Level await has moved to stage 3 stage 4 (see namo's comment), so the answer to your question How can I use async/await at the top level? is to just use await:
const text = await Promise.resolve('Hey there');
console.log('outside: ' + text)
Of if you want a main() function: add await to the call to main() :
async function main() {
var value = await Promise.resolve('Hey there');
console.log('inside: ' + value);
return value;
}
var text = await main();
console.log('outside: ' + text)
Compatibility
v8 since Oct 2019
the REPL in Chrome DevTools, Node.js and Safari web inspector
Node v13.3+ behind the flag --harmony-top-level-await
TypeScript 3.8+ (issue)
Deno since Oct 2019
Webpack#v5.0.0-alpha.15

To give some further info on top of current answers:
The contents of a node.js file are currently concatenated, in a string-like way, to form a function body.
For example if you have a file test.js:
// Amazing test file!
console.log('Test!');
Then node.js will secretly concatenate a function that looks like:
function(require, __dirname, ... perhaps more top-level properties) {
// Amazing test file!
console.log('Test!');
}
The major thing to note, is that the resulting function is NOT an async function. So you cannot use the term await directly inside of it!
But say you need to work with promises in this file, then there are two possible methods:
Don't use await directly inside the function
Don't use await at all
Option 1 requires us to create a new scope (and this scope can be async, because we have control over it):
// Amazing test file!
// Create a new async function (a new scope) and immediately call it!
(async () => {
await new Promise(...);
console.log('Test!');
})();
Option 2 requires us to use the object-oriented promise API (the less pretty but equally functional paradigm of working with promises)
// Amazing test file!
// Create some sort of promise...
let myPromise = new Promise(...);
// Now use the object-oriented API
myPromise.then(() => console.log('Test!'));
It would be interesting to see node add support for top-level await!

You can now use top level await in Node v13.3.0
import axios from "axios";
const { data } = await axios.get("https://api.namefake.com/");
console.log(data);
run it with --harmony-top-level-await flag
node --harmony-top-level-await index.js

The actual solution to this problem is to approach it differently.
Probably your goal is some sort of initialization which typically happens at the top level of an application.
The solution is to ensure that there is only ever one single JavaScript statement at the top level of your application. If you have only one statement at the top of your application, then you are free to use async/await at every other point everwhere (subject of course to normal syntax rules)
Put another way, wrap your entire top level in a function so that it is no longer the top level and that solves the question of how to run async/await at the top level of an application - you don't.
This is what the top level of your application should look like:
import {application} from './server'
application();

i like this clever syntax to do async work from an entrypoint
void async function main() {
await doSomeWork()
await doMoreWork()
}()

Other solutions were lacking some important details for POSIX compliance:
You need to ...
Report a 0 exit status on success and non-zero on fail.
Emit errors to stderr output stream.
#!/usr/bin/env node
async function main() {
// ... await stuff ...
}
// POSIX compliant apps should report an exit status
main()
.then(() => {
process.exit(0);
})
.catch(err => {
console.error(err); // Writes to stderr
process.exit(1);
});
If you're using a command line parser like commander, you may not need a main().
Example:
#!/usr/bin/env node
import commander from 'commander'
const program = new commander.Command();
program
.version("0.0.1")
.command("some-cmd")
.arguments("<my-arg1>")
.action(async (arg1: string) => {
// run some async action
});
program.parseAsync(process.argv)
.then(() => {
process.exit(0)
})
.catch(err => {
console.error(err.message || err);
if (err.stack) console.error(err.stack);
process.exit(1);
});

Node -
You can run node --experimental-repl-await while in the REPL. I'm not so sure about scripting.
Deno -
Deno already has it built in.

For Browser you need to add type="module"
without type="module"
<script>
const resp = await fetch('https://jsonplaceholder.typicode.com/users');
const users = await resp.json();
console.log(users)
</script>
with type="module"
<!--script type="module" src="await.js" -->
<script type="module">
const resp = await fetch('https://jsonplaceholder.typicode.com/users');
const users = await resp.json();
console.log(users)
</script>

You need to add type in package.json
"type": "module"
You are good to go.
import axios from 'axios';
const res = await axios.get('https://api.github.com/users/wesbos');
console.log(res.data);
Remember if you change type of document then you must have to write code in ES6 way.

Now with ECMAScript22, we can use await at the top-level module.
This is an example with ( await top-level ):
const response = await fetch("...");
console.log(response):
an other example without (await top-level )
async function callApi() {
const response = await fetch("...");
console.log(response)
}
callApi()

In NodeJS 14.8+, you can use top-level await module (#3 solution). You can rename also .js to .mjs (ES module) instead of .js (.cjs CommonJS).

If your only goal is to control the execution order of asynchronous code mixed with other code for testing purposes, you could wrap the entire top-level code inside of an immediately-invoked function expression (IIFE) defined as an async function. In the example from the question, you would then add await before calling main().
You can use this pattern when your code is not already in an async function or at the top level body of a module. In other words, if you're just testing a bunch of code inside of a js file and using tools like Live Server, RunJs, or any other type of JavaScript playground to watch the console window, wrap all of your code in an IIFE defined as async and use the await keyword when you want to wait for asynchronous code to finish before executing the next line.
let topLevelIIFE = (async () => {
async function main() {
var value = await Promise.resolve('Hey there');
console.log('inside: ' + value);
return value;
}
var text = await main();
console.log('outside: ' + text);
})()
You would not need to use this pattern when running the code specified in the body of the IIFE inside of the REPL in Chrome DevTools or another browser REPL tool that behaves similarly.

Since main() runs asynchronously it returns a promise. You have to get the result in then() method. And because then() returns promise too, you have to call process.exit() to end the program.
main()
.then(
(text) => { console.log('outside: ' + text) },
(err) => { console.log(err) }
)
.then(() => { process.exit() } )

Async / await vs then which is the best for performance?

I have a simple code in JavaScript that execute a request in an API and return the response, simple. But in this case I will have thousands of requests. So, which one of the code options will perform better, and why. Also which one is recommended as good pratices these days?
First options is using the .then to resolve the promises and the seccond one is using async / await.
In my tests the two options had very similar results without significant differences, but I'm not sure in scale.
// Using then
doSomething(payload) {
const url = 'https://link-here/consultas';
return this.axios.get(url, {
params: {
token: payload.token,
chave: payload.chave,
},
}).then(resp => resp.data);
}
// Using Async / await
async doSomething(payload) {
const url = 'https://link-here/consultas';
const resp = await this.axios.get(url, {
params: {
token: payload.token,
chave: payload.chave,
},
});
return resp.data;
}
Any explanation will be of great value.

From a performance point of view, await is just an internal version of .then() (doing basically the same thing). The reason to choose one over the other doesn't really have to do with performance, but has to do with desired coding style or coding convenience. Certainly, the interpreter has a few more opportunities to optimize things internally with await, but its unlikely that should be how you decide which to use. If all else was equal, I would choose await for the reason cited above. But, I'd first choose which made the code simpler to write and understand and maintain and test.
Used properly, await can often save you a bunch of lines of code making your code simpler to read, test and maintain. That's why it was invented.
There's no meaningful difference between the two versions of your code. Both achieve the same result when the axios call is successful or has an error.
Where await could make more of a convenience difference is if you had multiple successive asynchronous calls that needed to be serialized. Then, rather than bracketing them each inside a .then() handler to chain them properly, you could just use await and have simpler looking code.
A common mistake with both await and .then() is to forget proper error handling. If your error handling desire in this function is to just return the rejected promise, then both of your versions do that identically. But, if you have multiple async calls in a row and you want to do anything more complex than just returning the first rejection, then the error handling techniques for await and .then()/.catch() are quite different and which seems simpler will depend upon the situation.

There should be some corrections in this thread. await and .then are going to give very different results, and should be used for different reasons.
await will WAIT for something, and then continue to the next line. It's also the simpler of the two because it behaves mechanically more like synchronous behavior. You do step #1, wait, and then continue.
console.log("Runs first.");
await SomeFunction();
console.log("Runs last.");
.then splits off from the original call and starts operating within its own scope, and will update at a time the original scope cannot predict. If we can put semantics aside for a moment, it's "more asynchronous," because it leaves the old scope and branches off into a new one.
console.log("Runs first.");
SomeFunction().then((value) => {console.log("Runs last (probably). Didn't use await on SomeFunction().")})
console.log("Runs second (probably).");

As more explanation to #user280209 answer let's consider the following function which returns promise and compare its execution with .then() and async await.
function call(timeout) {
return new Promise((resolve, reject) => {
setTimeout(() => {
console.log(`This call took ${timeout} seconds`);
resolve(true);
}, timeout * 1000);
});
}
With .then()
(async () => {
call(5).then((r) => {
console.log(r);
});
await call(2); //This will print result first
await call(1);
})();
When running the above call the logs will be
This call took 2 seconds
This call took 1 seconds
This call took 5 seconds
true
As we can see .then() didn't pause the execution of its below line until it completes.
With async/wait
(async () => {
await call(5); //This will print result first
await call(2);
await call(1);
})();
When run the above function logs will be
This call took 5 seconds
This call took 2 seconds
This call took 1 seconds
So I think if your promise's result won't be used in the following lines, .then() may be better.

For those saying await blocks the code until the async call returns you are missing the point. "await" is syntactic sugar for a promise.then(). It is effectively wrapping the rest of your function in the then block of a promise it is creating for you. There is no real "blocking" or "waiting".
run();
async function run() {
console.log('running');
makePromises();
console.log('exiting right away!');
}
async function makePromises() {
console.log('make promise 1');
const myPromise = promiseMe(1)
.then(msg => {
console.log(`What i want to run after the promise is resolved ${msg}`)
})
console.log('make promise 2')
const msg = await promiseMe(2);
console.log(`What i want to run after the promise is resolved via await ${msg}`)
}
function promiseMe(num: number): Promise<string> {
return new Promise((resolve, reject) => {
console.log(`promise`)
resolve(`hello promise ${num}`);
})
}
The await line in makePromises does not block anything and the output is:
running
make promise 1
promise
make promise 2
promise
exiting right away!
What i want to run after the promise is resolved hello promise 1
What i want to run after the promise is resolved via await hello promise 2

Actually.
Await/Async can perform more efficiently as Promise.then() loses the scope in which it was called after execution, you are attaching a callback to the callback stack.
What it causes is: The system now has to store a reference to where the .then() was called. In case of error it has to correctly point to where the error happens, otherwise, without the scope (as the system resumed execution after called the Promise, waiting to comeback to the .then() later) it isn't able to point to where the error happened.
Async/Await you suspend the exection of the method where it is being called thus preserving reference.

If we just consider performance(time taken) then it actually depends on whether your operations are serial or parallel. If your tasks are serial then there will be no difference between await and .then. But if your tasks are parallel then .then will take less time. Consider the following example
let time = Date.now();
// first task takes 1.5 secs
async function firstTask () {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve(1);
},1500)
})
}
// second task takes 2 secs
async function secondTask () {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve(2);
},2000)
})
}
// using await
async function call(){
const d1 = await firstTask();
const d2 = await secondTask();
console.log(Date.now()-time, d1+d2)
}
call()
// using .then
async function call2(){
let d1=null,d2=null;
firstTask().then(data => {
d1=data;
if(d2){
console.log(Date.now()-time, d1+d2);
}
})
secondTask().then(data => {
d2=data;
if(d1){
console.log(Date.now()-time, d1+d2);
}
})
}
call2()
Here are the two tasks, first takes 1.5 secs and second takes 2 secs. Call function uses await where as call2 function uses .then . The output is as follows
From call2 2012 3
From call 3506 3
I hope it helps.

As far as I understand .then() and await are not the same thing. An async function won't proceed with the next command until the promise is resolved/rejected since it's basically an implementation of generators. On the contrast, in the case of .then(), the execution of the function will proceed with the next command and the resolve/reject callback will be executed "when there's time" aka when the current event loop (not entirely sure about that part) will be completed.
tldr; on a single promise await and .then() behave similarly but when one promise needs another one to be resolved first then the two of them behave entirely different

Many answer have been provided to this question already. However, to point out key information in the answers above and from my understanding, note below point:
only use await when not handling error return
if no crucial need for error handling use await instead
use .then .catch if returned error message or data is crucial for debugging / or proper error handling instead of try catch for await
Choose any prefer method from code sample below
const getData = (params = {name: 'john', email: 'ex#gmail.com'}) => {
return axios.post(url, params);
}
// anywhere you want to get the return data
// using await
const setData = async () => {
const data = await getData();
}
// to handle error with await
const setData = async () => {
try {
const data = await getData();
}
catch(err) {
console.log(err.message);
}
}
// using .then .catch
const setData = () => {
var data;
getData().then((res) => {
data = res.data; console.log(data)
}).catch((err) => {
console.log(err.message);
});
}

Difference of using async / await vs promises?

I am looking for a answer on what to use in my nodeJS app.
I have code which handles my generic dB access to mssql. This code is written using an async functions and then I used a promise to call that function and all works fine.
As my app is getting bigger and code larger I am planning to move some of the logic into functions and then call them.
So my question is: is there a drawback to using a mix of async/await and promises or does it really not matter?
Async / await makes it easier to write more readable code as I have to read and write to multiple db’s before I return something and I need results of some of these.
So the question is what is the better approach?
Async / await on dB layer that’s set and can’t change
The logic layer async / await which would allow me a async / and await on the function call or if I go with promise for logic then I am stuck with promise on function call.
So I hope someone can give me more insight if one has more advantages than the other, besides being able to write cleaner code.

async/await and promises are closely related. async functions return promises, and await is syntactic sugar for waiting for a promise to be resolved.
The only drawback from having a mix of promises and async functions might be readability and maintainability of the code, but you can certainly use the return value of async functions as promises as well as await for regular functions that return a promise.
Whether you choose one vs the other mostly depends on availability (does your node.js / browser support async?) and on your aesthetic preference, but a good rule of thumb (based on my own preference at the time of writing) could be:
If you need to run asynchronous code in series: consider using async/await:
return asyncFunction()
.then(result => f1(result))
.then(result2 => f2(result2));
vs
const result = await asyncFunction();
const result2 = await f1(result);
return await f2(result2);
If you need nested promises: use async/await:
return asyncFunction()
.then(result => {
return f1(result)
.then(result2 => f2(result, result2);
})
vs
const result = await asyncFunction();
const result2 = await f1(result);
return await f2(result, result2);
If you need to run it in parallel: use promises.
return Promise.all(arrayOfIDs.map(id => asyncFn(id)))
It has been suggested you can use await within an expression to await multiple tasks like so:
*note, this still awaits in sequence from left to right, which is OK if you don't expect errors. Otherwise the behaviour is different due to fail fast behaviour of Promise.all()
const [r1, r2, r3] = [await task1, await task2, await task3];
(async function() {
function t1(t) {
console.time(`task ${t}`);
console.log(`start task ${t}`);
return new Promise((resolve, reject) => {
setTimeout(() => {
console.timeEnd(`task ${t}`);
resolve();
}, t);
})
}
console.log('Create Promises');
const task1 = t1(100);
const task2 = t1(200);
const task3 = t1(10);
console.log('Await for each task');
const [r1, r2, r3] = [await task1, await task2, await task3];
console.log('Done');
}())
But as with Promise.all, the parallel promises need to be properly handled in case of an error. You can read more about that here.
Be careful not to confuse the previous code with the following:
let [r1, r2] = [await t1(100), await t2(200)];
function t1(t) {
console.time(`task ${t}`);
console.log(`start task ${t}`);
return new Promise((resolve, reject) => {
setTimeout(() => {
console.timeEnd(`task ${t}`);
resolve();
}, t);
})
}
console.log('Promise');
Promise.all([t1(100), t1(200), t1(10)]).then(async() => {
console.log('Await');
let [r1, r2, r3] = [await t1(100), await t1(200), await t1(10)]
});
Using these two methods is not equivalent. Read more about the difference.
In the end, Promise.all is a cleaner approach that scales better to an arbitrary number of tasks.

Actually it depends on your node version, But if you can use async/await then your code will be more readable and easier to maintain.
When you define a function as 'async' then it returns a native Promise, and when you call it using await it executes Promise.then.
Note:
Put your await calls inside a try/catch, because if the Promise fails it issues 'catch' which you can handle inside the catch block.
try{
let res1 = await your-async-function(parameters);
let res2 = await your-promise-function(parameters);
await your-async-or-promise-function(parameters);
}
catch(ex){
// your error handler goes here
// error is caused by any of your called functions which fails its promise
// this methods breaks your call chain
}
also you can handle your 'catch' like this:
let result = await your-asyncFunction(parameters).catch((error)=>{//your error handler goes here});
this method mentioned does not produce an exception so the execution goes on.
I do not think there is any performance difference between async/await other than the native Promise module implementation.
I would suggest to use bluebird module instead of native promise built into node.

At this point the only reason to use Promises is to call multiple asynchronous jobs using Promise.all() Otherwise you’re usually better with async/await or Observables.

Its depending upon what approach you are good with, both promise and async/await are good, but if you want to write asynchronous code, using synchronous code structure you should use async/await approach.Like following example, a function return user with both Promise or async/await style.
if we use Promise:
function getFirstUser() {
return getUsers().then(function(users) {
return users[0].name;
}).catch(function(err) {
return {
name: 'default user'
};
});
}
if we use aysnc/await
async function getFirstUser() {
try {
let users = await getUsers();
return users[0].name;
} catch (err) {
return {
name: 'default user'
};
}
}
Here in promise approach we need a thenable structure to follow and in async/await approach we use 'await' to hold execution of asynchronous function.
you can checkout this link for more clarity Visit https://medium.com/#bluepnume/learn-about-promises-before-you-start-using-async-await-eb148164a9c8

Yesterday I made a tentative decision to switch from using Promises to using Async/Await, independent of nodejs, based on the difficulty in accessing previous values in the Promise chain. I did come up with a compact solution using 'bind' to save values inside the 'then' functions, but Async seemed much nicer (and it was) in allowing direct access to local variables and arguments. And the more obvious advantage of Async/Await is, of course, the elimination of the distracting explicit 'then' functions in favor of a linear notation that looks much like ordinary function calls.
However, my reading today uncovered problems with Async/Await, which derail my decision. I think I'll stick with Promises (possibly using a macro preprocessor to make the 'then' functions look simpler) until Async/Await gets fixed, a few years from now.
Here are the problems I found. I'd love to find out that I am wrong, that these have easy solutions.
Requires an outer try/catch or a final Promise.catch(), otherwise errors and exceptions are lost.
A final await requires either a Promise.then() or an extra outer async function.
Iteration can only be properly done with for/of, not with other iterators.
Await can only wait for only one Promise at a time, not parallel Promises like Promise chains with Promise.all.
Await doesn't support Promise.race(), should it be needed.

Angular & async / await

I am using the following in my angular app:
let getName = greenlet( async username => {
let url = `https://api.github.com/users/${username}`
let res = await fetch(url)
let profile = await res.json()
return profile.name
})
console.log(await getName('developit'));
Angular seems to be changing this 'await' into 'yield':
How do i use this within my Angular5 application? Thanks.

Babel changes async/await in the browser into generator functions, which utilize the yield keyword. Yields only work when they are in the correct context; specifically the next stage will be ensuring that the yield appears inside a generator function (you can read more about generators, but basically they are identified by a * in the function signature, e.g. function *doSomething().
A generator function will not get created if you have not correctly managed your async keywords. Babel will convert that await into a generator, but because the outer function is not async, it won't create the generator wrapper, thus the error. Some IDEs will report this error before you compile, but that's what the error you are seeing means.
You mentioned that this console.log is sitting inside the ngOnInit lifecycle hook; that function call is not by itself asynchronous. You can decorate it with async, but I wouldn't recommend that (it works, but what does it actually mean?). Instead you can try calling an explicitly async function and just ignore the returned promise:
ngOnInit() {
this.someFunction();
}
async someFunction() {
console.log(await getName('developit'));
}
We'll assume for now that greenlet knows what to do with the async function it has been handed (does it resolve the promise?)