ES6 - Object Extensions-alljchome-开发者的教程家园

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ES6 - Object Extensions

String extension

Some popular methods added to the String object in ES6 are −

Sr.No	Method & Description
1	determines whether a string begins with the characters of a specified string. Returns true or false
2	str.endsWith(searchString[, length]) determines whether a string ends with the characters of a specified string. Returns true/false
3	str.includes(searchString[, position]) determines whether one string may be found within another string
4	str.repeat(count) constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together

Regex extensions

In a regular expression, for example, /[A-Z]/g, the beginning and ending / are called depmiters. Anything after the closing depmiter is called a modifier. ES6 adds a new modifier /g where g stands for global. This match all instances of the pattern in a string, not just one.

Example

The following example searches and returns all upper-case characters in the string.


<script>
   let str =  JJavascript is Fun to Work , very Fun  
   let regex = /[A-Z]/g // g stands for global matches
   let result = str.match(regex);
   console.log(result)
</script>

The output of the above code will be as given below −


["J", "J", "F", "W", "F"]

Regular expression searches are case-sensitive. To turn-off case-sensitivity, use the /i modifier.

Example

The following example performs a case insensitive global match. The example replaces fun with enjoyable.


<script>
   // /gi global match ignore case

   let str =  Javascript is fun to Work , very Fun  
   let regex = /Fun/gi;
   console.log(str.replace(regex, enjoyable ));
   console.log(str)
   console.log(str.search(regex))
</script>

The output of the above code will be as shown below −


Javascript is enjoyable to Work , very enjoyable
Javascript is fun to Work , very Fun
15

Number

Some popular methods added to the Number object in ES6 are −

Sr.No	Method & Description
1	Number.isFinite(value) method determines whether the passed value is a finite number. Returns true/false.
2	Number.isNaN(value) returns true if the given value is NaN and its type is Number; otherwise, false.
3	Number.parseFloat(string) A floating-point number parsed from the given value. If the value cannot be converted to a number, NaN is returned.
4	Number.parseInt(string,[ radix]) method parses a string argument and returns an integer of the specified radix or base.

Math

Some popular methods added to the Math object in ES6 are −

Sr.No	Method & Description
1	Math.sign() function returns the sign of a number, indicating whether the number is positive, negative or zero.
2	Math.trunc() function returns the integer part of a number by removing any fractional digits.

Methods of Array in ES6

The table given below highpghts the different array methods in ES6 along with the description.

Sr.No	Method & Description
1	copyWithin() shallow copies part of an array to another location in the same array and returns it without modifying its length.
2	entries() method returns a new Array Iterator object that contains the key/value pairs for each index in the array.
3	find() method returns the value of the first element in the array that satisfies the provided testing function. Otherwise undefined is returned..
4	fill() method fills all the elements of an array from a start index to an end index with a static value. It returns the modified array.
5	Array.of() method creates a new Array instance from a variable number of arguments, regardless of number or type of the arguments.
6	Array.from() method creates a shallow copy from an array pke or iterable object.

Object

Methods related to Object function are mentioned below in the table along with the respective description.

Sr.No	Method & Description
1	Object.is() method determines whether two values are the same value
2	Object.setPrototypeOf() method sets the prototype of a specified object to another object or null.
3	Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

ES6 - Object Extensions

String extension

Regex extensions

Example

Example

Number

Math

Methods of Array in ES6

Object

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