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Kurapati Mahesh
Kurapati Mahesh

Posted on

Javascript: String Search methods

1. indexOf

inputStr.indexOf(str) - returns first occurrence of mentioned str in given inputStr

inputStr.indexOf(str, 10) - returns first occurrence of string after 10 position.

const str = 'Hi, Welcome to Vishwaks JS articles';

str.indexOf('Welcome');
> 4

str.indexOf('Welcome', 10); // Search after 10th position.
> -1

const str = 'Hi, Welcome to Vishwaks JS articles - Welcome to JustCode';

str.indexOf('Welcome', 10); // Search after 10th position.
> 38

str.indexOf('hi'); // case sensitive
> -1
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2. lastIndexOf

Same like indexOf but searches from end of the string.

inputStr.lastIndexOf(str) - returns last occurrence of mentioned str in given inputStr

inputStr.lastIndexOf(str, 10) - returns last occurrence of string from 10 index to beginning.

const testString = "locate string locate";

testString.lastIndexOf('locate');
> 14

testString.lastIndexOf('locate', 14);
> 14

testString.lastIndexOf('string');
> 7

testString.lastIndexOf('string', 6);
> -1

testString.lastIndexOf('string', 15);
> 7

testString.lastIndexOf('String'); // case sensitive
> -1

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3. search

search() is same like indexOf but won't allow position param.

Whereas, indexOf won't support regex based search but search() supports it.

const str = 'Hi, Welcome to Vishwaks JS articles 1234';

str.search('Welcom');
> 4

str.search(/\d/);
> 36

str.search(1234);
> 36

str.search('welcome'); // case sensitive
> -1

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4. match

match() searches specified string same like search but returns an array of matched strings.

const str = 'Hi, Welcome to Vishwaks JS articles 1234';

str.match('Hi');
> ['Hi', index: 0, input: 'Hi, Welcome to Vishwaks JS articles 1234', groups: undefined]

str.match('Welcome');
> ['Welcome', index: 4, input: 'Hi, Welcome to Vishwaks JS articles 1234', groups: undefined]

str.match(/\d/);
> ['1', index: 36, input: 'Hi, Welcome to Vishwaks JS articles 1234', groups: undefined]

str.match('hi'); // case sensitive
> null
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5. includes

includes() returns true if string found.

const str = 'Hi, Welcome to Vishwaks JS articles 1234';

str.includes(1234);
> true

str.includes('JS');
> true

str.includes('test');
> false

str.includes('hi'); // case sensitive
> false

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6. startsWith

Returns boolean if string starts with specified value.

str.startsWith('test') - if 'str' starts with 'test' then returns true otherwise false.

str.startsWith('test', 10) - 10th index in string starts with test or not.

const str = 'Hi, Welcome to Vishwaks JS articles';

str.startsWith('Hi');
> true

str.startsWith('Welcome', 4);
> true

str.startsWith('hi'); // case sensitive
> false
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7. endsWith

Returns boolean if string ends with specified value.

str.endsWith('test') - if 'str' ends with 'test' then returns true otherwise false.

str.endsWith('test', 10) - till 10th index in string ends with test or not.

const str = 'Hi, Welcome to Vishwaks JS articles';

str.endsWith('articles');
> true

str.endsWith('to', 14); // Check first 14 characters ends with to.
> true

str.endsWith('aRticles'); // case sensitive
> false
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There are two more methods which are from RegExp are test() & exec() does the same.

All the above methods are case sensitive methods.

Thanks,

You can follow me here: https://twitter.com/urstrulyvishwak

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