174 lines
3.6 KiB
Markdown
174 lines
3.6 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# isSafeInteger
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> Test if a value is a number having a safe integer value.
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<section class="usage">
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## Usage
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```javascript
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var isSafeInteger = require( '@stdlib/assert/is-safe-integer' );
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```
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#### isSafeInteger( value )
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Tests if a value is a `number` having a safe `integer` value.
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<!-- eslint-disable no-new-wrappers -->
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```javascript
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var Number = require( '@stdlib/number/ctor' );
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var bool = isSafeInteger( 5.0 );
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// returns true
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bool = isSafeInteger( new Number( 5.0 ) );
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// returns true
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bool = isSafeInteger( 2.0e200 );
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// returns false
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bool = isSafeInteger( -3.14 );
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// returns false
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bool = isSafeInteger( null );
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// returns false
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```
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#### isSafeInteger.isPrimitive( value )
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Tests if a `value` is a primitive `number` having a safe `integer` value.
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<!-- eslint-disable no-new-wrappers -->
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```javascript
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var Number = require( '@stdlib/number/ctor' );
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var bool = isSafeInteger.isPrimitive( -3.0 );
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// returns true
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bool = isSafeInteger.isPrimitive( new Number( -3.0 ) );
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// returns false
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```
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#### isSafeInteger.isObject( value )
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Tests if a `value` is a `Number` object having a safe `integer` value.
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<!-- eslint-disable no-new-wrappers -->
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```javascript
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var Number = require( '@stdlib/number/ctor' );
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var bool = isSafeInteger.isObject( 3.0 );
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// returns false
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bool = isSafeInteger.isObject( new Number( 3.0 ) );
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// returns true
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- An integer valued number is "safe" when the number can be exactly represented as a [double-precision floating-point number][ieee754]. For example,
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```javascript
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var MAX_SAFE_INTEGER = require( '@stdlib/constants/float64/max-safe-integer' );
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// returns 9007199254740991
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var x = 9007199254740992;
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// returns 9007199254740992
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var y = 9007199254740993;
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// returns 9007199254740992
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var bool = ( x === y );
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// returns true
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```
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In this example, `x` and `y` should be distinct, but they are not due to constraints imposed by storing numeric values in [double-precision floating-point format][ieee754]. "Safe" integers are thus [double-precision floating-point numbers][ieee754] having integer values with unequivocal binary representations.
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint-disable no-new-wrappers -->
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<!-- eslint no-undef: "error" -->
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```javascript
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var Number = require( '@stdlib/number/ctor' );
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var isSafeInteger = require( '@stdlib/assert/is-safe-integer' );
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var bool = isSafeInteger( -5.0 );
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// returns true
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bool = isSafeInteger( 0.0 );
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// returns true
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bool = isSafeInteger( new Number( 5.0 ) );
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// returns true
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bool = isSafeInteger( 2.0e200 );
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// returns false
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bool = isSafeInteger( 5.256 );
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// returns false
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bool = isSafeInteger( 1.0/0.0 );
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// returns false
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bool = isSafeInteger( -1.0/0.0 );
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// returns false
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bool = isSafeInteger( NaN );
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// returns false
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bool = isSafeInteger( '5' );
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// returns false
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bool = isSafeInteger( null );
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// returns false
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
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</section>
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<!-- /.links -->
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