How to use the Array filter() method in JS

This time I will show you how to use the Array filter() method in JS. What are the precautions for using the Array filter() method in JS. The following is a practical case. Let’s take a look. .

What is a sparse array

The indexes of array elements do not have to be consecutive, there can be gaps between them. Every

javaScript array has a length property. For non-sparse arrays, this property is the number of array elements; for sparse arrays, length is greater than the number of all elements.

The Array filter() method skips missing elements in a sparse array, and its return array is always dense.

(1) Compress the vacancies of the sparse array:

var dense = sparse.filter( function(currentValue)
{ 
return true; 
}
);

(2) Compress the vacancies of the sparse array, and

delete undefined and null elements:

var dense = sparse.filter( function(currentValue) 
{ 
return currentValue !== undefined && currentValue!= null;
} 
)

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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