10 javascript string methods you should know
In this post I will summarize 10 javascript string methods you should at least known according to me.
If interested read here 10 javascript array methods you should know .
String is anything inside single or double quotes.
Here are 10 javascript string methods you should know.
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startsWith()
Check if string starts with specified character(s).
const str = 'JavaScript is amazing'; console.log(str.startsWith('JavaScript')); // true console.log(str.startsWith('Java')); // true console.log(str.startsWith('javascript')); // false // position is optional // if not specified, the default value is 0 console.log(str.startsWith('Script', 4)); // true console.log(str.startsWith('SCRIPT', 4)); // false
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endsWith()
Check if string ends with specified character(s).
const str = 'JavaScript is amazing'; // check if ends with 'amazing' console.log(str.endsWith('amazing')); // true console.log(str.endsWith('ing')); // true console.log(str.endsWith('Amazing')); // false // length is optional // if not specified, the default value is length of the string console.log(str.endsWith('is', 13)); // true console.log(str.endsWith('i', 13)); // false console.log(str.endsWith('s', 13)); // true
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includes()
Check if string contains specified character(s).
const str = 'JavaScript is amazing'; console.log(str.includes('Script')); // true console.log(str.includes('script')); // false console.log(str.includes(' ')); // true console.log(str.includes('array')); // false
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slice()
Copy some part of string without modifying the original one.
const str = 'JavaScript is amazing'; // Default start index is 0 console.log(str.slice()); // 'JavaScript is amazing' // start copy at index 4 console.log(str.slice(4)); // 'Script is amazing' // end copy at index 10(character at this index will not be included) console.log(str.slice(0, 10)); // 'JavaScript'
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toUpperCase()
Convert string into upper case.
const str = 'JavaScript is amazing'; console.log(str.toUpperCase()); // 'JAVASCRIPT IS AMAZING'
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toLowerCase()
Convert string into lower case.
const str = 'JavaScript is amazing'; console.log(str.toLowerCase()); // 'javascript is amazing'
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charAt()
Return character at specified position.
const str = 'JavaScript is amazing'; console.log(str.charAt()); // 'J' console.log(str.charAt(11)); // 'i' console.log(str.charAt(14)); // 'a' console.log(str.charAt(110)); // ''
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split()
Split string into array of substrings.
const str = 'JavaScript is amazing'; const strNew = 'JavaScript-is-amazing'; console.log(str.split()); // ["JavaScript is amazing"] // Separator string used to determine where to make each split console.log(str.split('S')); // ["Java", "cript is amazing"] console.log(str.split('is')); // ["JavaScript ", " amazing"] console.log(str.split(' ')); // ["JavaScript", "is", "amazing"] console.log(strNew.split('-')); // ["JavaScript", "is", "amazing"]
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replace()
Replaces specified value with another value in a string.
const str = 'JavaScript is amazing'; console.log(str.replace('JavaScript', 'Node.js')); // 'Node.js is amazing' // replace() method is case sensitive // replace will not work console.log(str.replace('Javascript', 'Node.js')); // 'JavaScript is amazing' // use regular expression for case insensitive console.log(str.replace(/Javascript/i, 'Node.js')); // 'Node.js is amazing' // replace() method replaces only the first match console.log(str.replace('a', 'A')); // 'JAvaScript is amazing' // to replace all matches, use regular expression console.log(str.replace(/a/g, 'A')); // 'JAvAScript is AmAzing'
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repeat()
Return new string with specified number of copies of existing string.
const str = 'JavaScript'; console.log(str.repeat(3)); // 'JavaScriptJavaScriptJavaScript' console.log(str.repeat(1)); // 'JavaScript' console.log(str.repeat(0)); // ''