<pre><code>function CheckValue(value, index, ar) { 
 if (index == 0) 
 return true; 
 else 
 return ar[index - 1] === " "; 
} 

// Create a string. 
var sentence = "The quick brown fox jumps over the lazy dog."; 

// Create an array that contains all characters that follow a space. 
var subset = [].filter.call(sentence, CheckValue); 


document.write(subset);
</code></pre>As per the official doc, I have seen filter method is called upon an array. But here things seem to be messed up. For the first time, I have seen this kind of example using filter method.
I am unable to understand that how this code is working under the hood.


```
function CheckValue(value, index, ar) {  
    if (index == 0)  
        return true;  
    else  
        return ar[index - 1] === " ";  
}  

// Create a string.  
var sentence = "The quick brown fox jumps over the lazy dog.";   

// Create an array that contains all characters that follow a space.  
var subset = [].filter.call(sentence, CheckValue);   


document.write(subset);  
``` 

As per the official doc, I have seen filter method is called upon an array. But here things seem to be messed up. For the first time, I have seen this kind of example using filter method.

I am unable to understand that how this code is working under the hood. 





A weird example of filter method in JavaScript

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