Question

How to check if a value is not in an array with TypeScript

Answer 1

const arr: string[] = ['javascript', 'typescript', 'nodejs', 'c++'];

if (!arr.includes('python')) {
    console.log('value is not in array');
} else {
    console.log('value is in array');
}
  
    
    
    
    
/*
run:
    
"value is not in array"
    
*/

 

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Answer 2

const arr: string[] = ['javascript', 'typescript', 'nodejs', 'c++'];

if (arr.indexOf('python') === -1) {
    console.log('value is not in array');
} else {
    console.log('value is in array');
}
  
    
    
    
    
/*
run:
    
"value is not in array"
    
*/

 

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Answer 3

const arr: string[] = ['javascript', 'typescript', 'nodejs', 'php'];

const str = 'PHP-PHP';

const found = arr.find((element) => {
  return element.toLowerCase() === str.toLowerCase();
});

console.log(found); 

if (found == undefined) {
    console.log('value is not in array');
} else {
    console.log('value is in array');
}
  
    
    
    
    
/*
run:
    
undefined     
"value is not in array"
    
*/

  
  

 

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