Tag: functions in javascript

Built-in/Predefined Methods in JavaScript

by abhishek kJavaScript / WebsitesLeave a Comment on Built-in/Predefined Methods in JavaScript

In JavaScript, however, a method is a function that belongs to an object. A JavaScript method is a property containing a function definition.

There is a long list of Built-in or pre-defined methods in JavaScript

Maths Methods in JavaScript

  • min() ->Returns the smallest of zero or more numbers.
  • pow() ->Returns base to the exponent power, that is, base exponent.
  • abs() ->Returns the absolute value of a number.
  • acos() ->Returns the arccosine (in radians) of a number.
  • asin() ->Returns the arcsine (in radians) of a number.
  • sin() ->Returns the sine of a number.
  • sqrt() ->Returns the square root of a number.
  • tan() ->Returns the tangent of a number.
  • atan() ->Returns the arctangent (in radians) of a number.
  • atan2() ->Returns the arctangent of the quotient of its arguments.
  • exp() ->Returns EN, where N is the argument, and E is Euler’s constant, the base of the natural logarithm.
  • floor() ->Returns the largest integer less than or equal to a number.
  • log() ->Returns the natural logarithm (base E) of a number.
  • max() ->Returns the largest of zero or more numbers.
  • ceil() ->Returns the smallest integer greater than or equal to a number.
  • cos() ->Returns the cosine of a number.
  • random() ->Returns a pseudo-random number between 0 and 1.
  • round() ->Returns the value of a number rounded to the nearest integer.
  • toSource() ->Returns the string “Math”.

Boolean Methods in JavaScript

  • toString() ->Returns a string of either “true” or “false” depending upon the value of the object.
  • toSource() ->Returns a string containing the source of the Boolean object; you can use this string to create an equivalent object.
  • valueOf() ->Returns the primitive value of the Boolean object.

String Methods in JavaScript

  • length() ->Returns the length of the string.
  • search() ->Executes the search for a match between a regular expression and a specified string.
  • split() ->Splits a String object into an array of strings by separating the string into substrings.
  • lastIndexOf() ->Returns the index within the calling String object of the last occurrence of the specified value, or -1 if not found.
  • charAt() ->Returns the character at the specified index.
  • match() ->Used to match a regular expression against a string.
  • charCodeAt() ->Returns a number indicating the Unicode value of the character at the given index.
  • concat()-Combines the text of two strings and returns a new string.
  • replace() ->Used to find a match between a regular expression and a string and to replace the matched substring with a new substring.
  • substr() ->Returns the characters in a string beginning at the specified location through the specified number of characters.
  • toLowerCase() ->Returns the calling string value converted to lower case.
  • toString() ->Returns a string representing the specified object.
  • toUpperCase() ->Returns the calling string value converted to uppercase.
  • valueOf() ->Returns the primitive value of the specified object.
  • toLocaleLowerCase() ->The characters within a string are converted to lower case while respecting the current locale.
  • toLocaleUpperCase() ->The characters within a string are converted to the upper case while respecting the current locale.
  • substring() ->Returns the characters in a string between two indexes into the string.

Array Methods in JavaScript

  • every() ->Returns true if every element in this array satisfies the provided testing function.
  • reduce() ->Apply a function simultaneously against two values of the array (from left-to-right) as to reduce it to a single value.
  • filter() ->Creates a new array with all of the elements of this array for which the provided filtering function returns true.
  • forEach() ->Calls a function for each element in the array.
  • indexOf() ->Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found.
  • join() ->Joins all elements of an array into a string.
  • slice() ->Extracts a section of an array and returns a new array.
  • some() ->Returns true if at least one element in this array satisfies the provided testing function.
  • toSource() ->Represents the source code of an object
  • lastIndexOf() ->Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found.
  • map() ->Creates a new array with the results of calling a provided function on every element in this array.
  • reduceRight() ->Apply a function simultaneously against two values of the array (from right-to-left) as to reduce it to a single value.
  • reverse() ->Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first.
  • shift() ->Removes the first element from an array and returns that element.
  • sort() ->Sorts the elements of an array.
  • splice() ->Adds and/or removes elements from an array.
  • toString() ->Returns a string representing the array and its elements.
  • pop() ->Removes the last element from an array and returns that element.
  • push()->Adds one or more elements to the end of an array and returns the new length of the array.

Date Methods in JavaScript

  • getTime() ->Returns the numeric value of the specified date as the number of milliseconds since January 1, 1970, 00:00:00 UTC.
  • setTime() ->Sets the Date object to the time represented by a number of milliseconds since January 1, 1970, 00:00:00 UTC.
  • getTimezoneOffset() ->Returns the time-zone offset in minutes for the current locale.
  • getUTCDate() ->Returns the day (date) of the month in the specified date according to universal time.
  • setUTCDate() ->Sets the day of the month for a specified date according to universal time.
  • getUTCDay() ->Returns the day of the week in the specified date according to universal time.
  • getUTCFullYear() ->Returns the year in the specified date according to universal time.
  • getUTCHours() ->Returns the hours in the specified date according to universal time.
  • getUTCMilliseconds() ->Returns the milliseconds in the specified date according to universal time.
  • getUTCMinutes() ->Returns the minutes in the specified date according to universal time.
  • getUTCMonth() ->Returns the month in the specified date according to universal time.
  • getUTCSeconds() ->Returns the seconds in the specified date according to universal time.
  • getYear() ->Deprecated – Returns the year in the specified date according to local time. Use getFullYear instead.
  • setYear() ->Deprecated – Sets the year for a specified date according to local time. Use setFullYear instead.
  • setDate() ->Sets the day of the month for a specified date according to local time.
  • getDate() ->Returns the day of the month for the specified date according to local time.
  • setFullYear() ->Sets the full year for a specified date according to local time.
  • setHours() ->Sets the hours for a specified date according to local time.
  • setMilliseconds() ->Sets the milliseconds for a specified date according to local time.
  • setMinutes() ->Sets the minutes for a specified date according to local time.
  • getMonth() ->Returns the month in the specified date according to local time.
  • setMonth() ->Sets the month for a specified date according to local time.
  • getSeconds() ->Returns the seconds in the specified date according to local time.
  • setSeconds() ->Sets the seconds for a specified date according to local time.
  • setUTCFullYear() ->Sets the full year for a specified date according to universal time.
  • setUTCHours() ->Sets the hour for a specified date according to universal time.
  • setUTCMilliseconds() ->Sets the milliseconds for a specified date according to universal time.
  • setUTCMinutes() ->Sets the minutes for a specified date according to universal time.
  • setUTCMonth() ->Sets the month for a specified date according to universal time.
  • setUTCSeconds() ->Sets the seconds for a specified date according to universal time.
  • toDateString() ->Returns the “date” portion of the Date as a human-readable string.
  • toGMTString() ->Deprecated – Converts a date to a string, using the Internet GMT conventions. Use toUTCString instead.
  • toString() ->Returns a string representing the specified Date object.
  • toTimeString() ->Returns the “time” portion of the Date as a human-readable string.
  • valueOf() ->Returns the primitive value of a Date object.
  • Date() ->Returns today’s date and time
  • getDay() ->Returns the day of the week for the specified date according to local time.
  • getFullYear() ->Returns the year of the specified date according to local time.
  • toLocaleDateString() ->Returns the “date” portion of the Date as a string, using the current locale’s conventions.
  • toLocaleFormat() ->Converts a date to a string, using a format string.
  • toLocaleTimeString() ->Returns the “time” portion of the Date as a string, using the current locale’s conventions.
  • getHours() ->Returns the hour in the specified date according to local time.
  • getMilliseconds() ->Returns the milliseconds in the specified date according to local time.
  • getMinutes() ->Returns the minutes in the specified date according to local time.

Few important links for learning:-

  1. Want to know the difference between Function and Method in JavaScript? Just click here.
  2. Want to know what is function and how to use them in JavaScript? Just click here.
  3. Want to know what are variables and how to use them in JavaScript? Just click here.
  4. Let’s see an example for User form validation in JavaScript. click here.
  5. Let’s understand JavaScript. what and how? click here.
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Predefined Functions in JavaScript

by abhishek kJavaScript / WebsitesLeave a Comment on Predefined Functions in JavaScript

Want to know what is function and how to use them in JavaScript? Just click here.

Every computer programming language has functions. Some functions are defined by the programmers while the code is being written while some functions are predefined when the language was built.

As every functions have three parts

  1. Function Declaration
  2. Function Definition.
  3. Function Call

In predefined functions, the first two points are already done inside the library which we include as a header file at the beginning of the program. we just have to call the function.

Few most common predefined functions that we use are:-

Functions to display something in JavaScript:-

alert(message) – It displays an alert box with a message specified in it.

confirm(message) – It will display the message with two buttons. “OK” and “Cancel”.

prompt(message) – Displays a box with the message passed. There the user can enter text in the prompt field, and choose OK or Cancel. If the user chooses OK, the string value entered in the field is returned and If the user chooses Cancel, a NULL value is returned.

Functions for conversion in JavaScript:-

parseFloat() – It returns floating-point numbers the same way as the parseInt function does, but looks for floating-point qualified strings and returns their value as afloat.

parseInt()– It converts a string to an integer returning the first integer encountered which is contained in the string. If no integer values are found such as in the string “written text”, then a value of 0 is returned.

Functions for comparison in JavaScript:-

eval()– Converts a string to integer or float value.

isNaN(value) – If the value passed is not a number, the boolean value of true is returned, if it is a number, it returns false.

escape(string) – It passes the string to be encoded and returns the encoded string. Encodes a string from ASCII into an ISO Latin-1 (ISO 8859-1) character set for HTML processing.

unescape() – Converts an ISO8859-1 character set to ASCII.

isFinite() – function determines whether the passed value is a finite number. If needed, the parameter is first converted to a number.

Functions for decoding and encoding in JavaScript:-

decodeURI() function decodes a Uniform Resource Identifier (URI) previously created by encodeURI or by a similar routine. decodeURIComponent()

decodeURIComponent() method decodes a Uniform Resource Identifier (URI) component previously created by encodeURIComponent() or by a similar routine. encodeURI

encodeURI() encodes a Uniform Resource Identifier (URI) by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character (will only be four escape sequences for characters composed of two “surrogate” characters). encodeURIComponent()

encodeURIComponent() encodes a Uniform Resource Identifier (URI) component by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character (will only be four escape sequences for characters composed of two “surrogate” characters).

There are more predefined functions but these were the important ones which are often used.

Few important links for learning:-

  1. Let’s see an example for User form validation in JavaScript. click here.
  2. Let’s understand javascript. what and how? click here.
  3. Want to know what is function and how to use them in JavaScript? Just click here.
  4. Want to know what are variables and how to use them in JavaScript? Just click here.
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