Remove and return the first element of a collection.
var shift = require( '@stdlib/utils/shift' );
Removes and returns the first element of a collection
. A collection
may be either an Array
, Typed Array
, or an array-like Object
(i.e., an Object
having a valid writable length
property).
var arr = [ 1.0, 2.0, 3.0, 4.0, 5.0 ];
var out = shift( arr );
// returns [ [ 2.0, 3.0, 4.0, 5.0 ], 1.0 ]
var bool = ( out[ 0 ] === arr );
// returns true
var lastValue = out[ 1 ];
// returns 1.0
In contrast to Array.prototype.shift
which returns only the removed element, the function also returns the shortened collection. For typed arrays having a length greater than 0
, the returned collection is a new typed array view.
var Float64Array = require( '@stdlib/array/float64' );
var arr = new Float64Array( 2 );
arr[ 0 ] = 1.0;
arr[ 1 ] = 2.0;
var out = shift( arr );
// returns [ <Float64Array>[ 2.0 ], 1.0 ]
var bool = ( out[ 0 ] === arr );
// returns false
bool = ( out[ 0 ].buffer === arr.buffer );
// returns true
var lastValue = out[ 1 ];
// returns 1.0
ArrayBuffer
. The function returns a new typed array view whose length is one less than the input typed array length. Accordingly, the function does not reduce the memory footprint of an input typed array.var Float64Array = require( '@stdlib/array/float64' );
var shift = require( '@stdlib/utils/shift' );
var arr;
var out;
var i;
arr = new Float64Array( 100 );
for ( i = 0; i < 100; i++ ) {
out = shift( arr );
arr = out[ 0 ];
console.log( 'Length: %d', arr.length );
}
console.log( arr );