Javascript Course

To access and use a variable or function dinamically, with Name from a String in JavaScript, just use the window object, with this syntax:


// For function
Here is some examples, see the explanations in code.

Using variable with name stored into a string

var vr_name = 'vr1'; // string with name of a variable

var vr1 = '';

// uses variable with name stored as string in vr_name
// window[vr_name] /window['vr1'] is the value of vr1
var site = 'http://'+ window[vr_name];

// Test
document.write(site); //

Using variable dinamically, with name stored into a string in object

// object with strings with variable names
var vr_name = {'v1':'vr1', 'v2':'vr2'};
var vr1 = '';
var vr2 = '';

// uses variable dinamically, with name stored as string in vr_name
var i = 2;
var site = 'https://'+ window[vr_name['v'+ i]];

// Test
document.write(site); //

Calling function with name stored into a string

function f1(a, b) {
 return a + b;

var f_name = 'f1'; // string with function name

// uses function with name stored as string in f_name
// window[f_name](parameters) calls the f1(parameters)
var sum = window[f_name](12, 23);

// Test
document.write(sum); // 35

Calling object method with name stored in string into an object

- Use: object['method_name'](parameters).
// object with strings with method names
var methods = {'m1':'hi1', 'm2':'hi2'};

// object with two methods
var obj = {
 'hi1': function(name) {
 return 'Hello dear '+ name;
 'hi2': function(name) {
 return 'Hola '+ name;

// uses object method with name stored as string in methods
var hi = obj[methods['m1']]('ME');

// Test
document.write(hi); // Hello dear ME

Daily Test with Code Example

Which tag create a highlighted bolded text?
<q> <strong> <em>
<p>Address: <strong></strong> - Tutorials.</p>
Which of these CSS codes displays the text bolded?
text-size: 18px; font-style: italic; font-weight: 800;
#id {
  font-weight: 800;
What JavaScript function can be used to call another function multiple times, to a specified time interval?
setInterval() setTimeout() push()
function someFunction() { alert(""); }
setInterval("someFunction()", 2000);
Click on the correctly defined variable in PHP.
var vname = 8; $vname = 8; $vname == 8;
$vname = 8;
echo $vname;
Using Variable and Function with Name from String in JavaScript

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