Page 99 - JavaScript

Use Array.prototype.slice like so:

var arrayLike = {
0: 'Value 0',
1: 'Value 1',
length: 2
};
var realArray = Array.prototype.slice.call(arrayLike);
realArray = [].slice.call(arrayLike); // Shorter version

realArray.indexOf('Value 1'); // Wow! this works

You can also use Function.prototype.call to call Array.prototype methods on Array-like objects
directly, without converting them:

5.1

var domList = document.querySelectorAll('#myDropdown option');

domList.forEach(function() {
// Do stuff
}); // Error! forEach is not defined.

Array.prototype.forEach.call(domList, function() {
// Do stuff
}); // Wow! this works

You can also use [].method.bind( arrayLikeObject ) to borrow array methods and glom them on to
your object:

5.1

var arrayLike = {
0: 'Value 0',
1: 'Value 1',
length: 2
};

arrayLike.forEach(function() {
// Do stuff
}); // Error! forEach is not defined.

[].forEach.bind(arrayLike)(function(val){
// Do stuff with val
}); // Wow! this works

Modifying Items During Conversion

In ES6, while using Array.from, we can specify a map function that returns a mapped value for the
new array being created.

6

Array.from(domList, element => element.tagName); // Creates an array of tagName's

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