while(i--) loop in javascript -

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i use while loop as:

while (i<some_value)

i saw while(i--) syntax , thought shorter , cooler , tried following in google-chrome.

var num_arr= [4,8,7,1,3];   var length_of_num_arr=num_arr.length;   while(length_of_num_arr--) console.log(num_arr);  [4, 8, 7, 1, 3]  [4, 8, 7, 1, 3]  [4, 8, 7, 1, 3]  [4, 8, 7, 1, 3]  [4, 8, 7, 1, 3] **// expected result**

but when try...

while((num_arr.length)--) console.log(num_arr); [4, 8, 7, 1] [4, 8, 7] [4, 8] [4] [] // why happening??

is there hidden things need understand use syntax?

arrays’ length property writable, , cut off elements or add empty slots appropriate when set it.

var items = [1, 2, 3, 4, 5]; items.length = 3; // items [1, 2, 3] items.length = 6; // items sparse array: [1, 2, 3, undefined × 3]

so, don’t that.


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