Easily hack fundamental JavaScript concepts with example
#javascript string
- String.charAt() => The String object’s charAt() method returns you a char from a string with her index number.
Example:
const sentence = “ The young boy jump over the child”;
const index = 6 ;
console.log(`the character at index ${index} is ${sentence. charAt(index)}`;
output => The character at index 6 is u
2. String.concat() => method concatenates the string arguments to the calling string and returns a new string.
Example:
const str1 = ‘I love’;
const str2 =’Bangladesh’;
cosole.log (str1.concat(‘ ’, str2));
output => I love Bangladesh
cosole.log (str2.concat(‘ ,’, str1));
output => Bangladesh, I love;
Syntax
str.concat(str2 [, ...strN])3.String.endsWith() => method narrate whether a string ends with the characters of a specified string, returning true to false as appropriate.
Example:
const str1 = ‘You are the best!’;
console.log(str1.endsWith(‘best’, 17));
// expected output: true
const str2 = ‘Is this a question’;
console.log(str2.endsWith(‘?’));
// expected output: false
Syntax
str.endsWith(searchString[, length])4.indexOf()=> method returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex. Returns -1 if the value is not found.
Example:
const paragraph = ‘The quick brown fox jumps over the lazy dog. If the dog barked, was it really lazy?’;
const searchTerm = ‘dog’;
const indexOfFirst = paragraph.indexOf(searchTerm);
console.log(`The index of the first “${searchTerm}” from the beginning is ${indexOfFirst}`);
// expected output: “The index of the first “dog” from the beginning is 40"
console.log(`The index of the 2nd “${searchTerm}” is ${paragraph.indexOf(searchTerm, (indexOfFirst + 1))}`);
// expected output: “The index of the 2nd “dog” is 52"
Syntax
str.indexOf(searchValue [, fromIndex])5.String.includes() =>the method determines whether one string may be found within another string, returning true or false as appropriate.
Example:
const sentence = ‘The quick brown fox jumps over the lazy dog.’;
const word = ‘fox’;
console.log(`The word “${word}” ${sentence.includes(word) ? ‘is’ : ‘is not’} in the sentence`);
// expected output: “The word “fox” is in the sentence”
Syntax
str.includes(searchString[, position])6.lastIndexOf()=> the method returns the index within the calling String an object of the last occurrence of the specified value, searching backward from fromIndex. Returns -1 if the value is not found.
Example:
const paragraph = ‘The quick brown fox jumps over the lazy dog. If the dog barked, was it really lazy?’;
const searchTerm = ‘lazy’;
console.log(`The index of the first “${searchTerm}” from the end is ${paragraph.lastIndexOf(searchTerm)}`);
// expected output: “The index of the first “dog” from the end is 52"
Syntax
str.lastIndexOf(searchValue[, fromIndex])
