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:

window['variable_name']

// For function
window['function_name'](parameters)
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 = 'coursesweb.net/';

// 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); // https://coursesweb.net/

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 = 'coursesweb.net/';
var vr2 = 'gamv.eu/';

// 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); // https://gamv.eu/

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

HTML
CSS
JavaScript
PHP-MySQL
What attribute makes an option from <select> selected?
checked="checked" selected="selected" disabled="disabled"
<select name="a_name">
 <option value="val1">Option 1</option>
 <option value="val2" selected="selected">Option 2</option>
</select>
What CSS value allows to create color gradients for background?
contain repeat-x linear-gradient
#id {
  background: linear-gradient(top left, #1f1, #fff, #11f);
}
What statement creates an array in JavaScript?
[] {} new Object()
var arr = [1, "CoursesWeb.net", "MarPlo.net"];
alert(arr[2]);
Indicate the PHP function used to redirect to other page.
function() header() switch()
header("Location: http://coursesweb.net/");
exit;
Using Variable and Function with Name from String in JavaScript

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