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Kurapati Mahesh
Kurapati Mahesh

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Javascript: String Search methods

#javascript #beginners #programming #webdev

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,

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