102 lines
1.7 KiB
Markdown
102 lines
1.7 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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# isUndefined
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> Test if a value is undefined.
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<section class="usage">
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## Usage
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```javascript
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var isUndefined = require( '@stdlib/assert/is-undefined' );
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```
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#### isUndefined( value )
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Tests if a `value` is `undefined`.
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<!-- eslint-disable no-undefined -->
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```javascript
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var bool = isUndefined( undefined );
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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="examples">
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## Examples
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<!-- eslint-disable no-undefined, no-restricted-syntax, no-empty-function -->
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<!-- eslint no-undef: "error" -->
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```javascript
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var isUndefined = require( '@stdlib/assert/is-undefined' );
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var bool;
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var x;
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bool = isUndefined( x );
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// returns true
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bool = isUndefined( undefined );
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// returns true
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bool = isUndefined( void 0 );
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// returns true
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bool = isUndefined( 'beep' );
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// returns false
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bool = isUndefined( 5 );
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// returns false
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bool = isUndefined( null );
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// returns false
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bool = isUndefined( true );
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// returns false
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bool = isUndefined( {} );
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// returns false
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bool = isUndefined( [] );
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// returns false
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bool = isUndefined( function foo() {} );
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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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</section>
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<!-- /.links -->
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