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JavaScript: Create a variable using a user-defined name

JavaScript Basic: Exercise-13 with Solution

Write a JavaScript exercise to create a variable using a user-defined name.

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>Create a variable using a user-defined name</title>
</head>
<body>

</body>
</html>

JavaScript Code:

var var_name = 'abcd';
var n = 120;
this[var_name] = n;
console.log(this[var_name])

Sample Output:

120

ES6 Version:

const var_name = 'abcd';
const n = 120;
this[var_name] = n;
console.log(this[var_name])

Live Demo:

See the Pen javascript-object-exercise-13 by w3resource (@w3resource) on CodePen.


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JavaScript: Tips of the Day

Promise.all method

const promise1 = Promise.resolve('First')
const promise2 = Promise.resolve('Second')
const promise3 = Promise.reject('Third')
const promise4 = Promise.resolve('Fourth')

const runPromises = async () => {
	const res1 = await Promise.all([promise1, promise2])
	const res2  = await Promise.all([promise3, promise4])
	return [res1, res2]
}

runPromises()
	.then(res => console.log(res))
	.catch(err => console.log(err))

The Promise.all method runs the passed promises in parallel. If one promise fails, the Promise.all method rejects with the value of the rejected promise. In this case, promise3 rejected with the value "Third". We're catching the rejected value in the chained catch method on the runPromises invocation to catch any errors within the runPromises function. Only "Third" gets logged, since promise3 rejected with this value.