Using Variable and Function with Name from String in JavaScript

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

<<-Add Pause in JavaScript .. -- Dynamic variables in JavaScript->>

Daily Test with Code Example

HTML

CSS

JavaScript

PHP-MySQL

Which tag is used to add lists into <ul> and <ol> elements?

<ul>
 <li>http://coursesweb.net/html/</li>
 <li>http://coursesweb.net/css/</li>
</ul>

Which value of the "display" property creates a block box for the content and ads a bullet marker?

block list-item inline-block

.some_class {
  display: list-item;
}

Which instruction converts a JavaScript object into a JSON string.

JSON.parse() JSON.stringify eval()

var obj = {
 "courses": ["php", "javascript", "ajax"]
};
var jsonstr = JSON.stringify(obj);
alert(jsonstr);    // {"courses":["php","javascript","ajax"]}

Indicate the PHP class used to work with HTML and XML content in PHP.

stdClass PDO DOMDocument

$strhtml = '<body><div id="dv1">CoursesWeb.net</div></body>';
$dochtml = new DOMDocument();
$dochtml->loadHTML($strhtml);
$elm = $dochtml->getElementById("dv1");
echo $elm->nodeValue;    // CoursesWeb.net

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