Important methods (math, integers, strings)

Math

Methods
Math.random() returns a decimal
Math.min(params_int) returns the min number which is in the sequence
Math.max(params_int) returns the max number in the sequence
Math.round() rounds the number to the nearest integer
Math.ceil() rounds the number up to the nearest integer (ceiling/high above)
Math.floor() rounds the number down to the nearest integer (ground/floor)

popular constants

Math.E // returns Euler’s number
Math.PI // returns PI
Math.SQRTnum // returns the square root of num

Converting to integer/floats

parseFloat(string/char) self explanatory
parseInt(string/char) self explanatory

toFixed(number_of_digits_after_dot) sets the number of digits of a decimal number after the dot. If number=0, then there are no digits after the space(Whole number). Returns string.
toPrecision(number_rounding_result) Rounds the number to a precision based on the number_rounding_result

Important values
undefined – The undefined property indicates that a variable has not been assigned a value.
nan – not a number (can be a char/string/bool..) useful method isNaN(string/char/int/float ect…)

Strings

Basic properties

 .length 

retrieves all characters from the string and returns an integer which specifies the amount of char in the given string.

Basic methods:

charAt(index)

returns a char specifying the character at a certain index position (index start from 0)

charCodeAt(index)

returns a integer specifying the unicode number where the char at the given index is located.

concat(params)

concatenates (glues) a string to the previous string( the string specified inside the argument is added to the previous one, multiple strings can be added inside the argument).

fromCharCode(unicode_num);

returns a char based on the unicode value argument input.

indexOf(string/char)

returns a integer index specifying the index position of the first char inside the argument,

common method

lastIndexOf(char)

returns a integer index specifying the index position of the last time the char inside the string appeared..

replace(_to_be_replaced,put_instead_of)

replaces a char/string, with the char/string specified as the first argument,

common method

slice(start_index,end_index)

returns the chars between the start_index and the end_index-1,

common method

split(criteria)

splits the strings inside the main string using a certain criteria (criteria example: “,” ” ” ect.)

common method

substr(start_included, counter_included)

extracts the string from start_included to counter_included. The method actually returns the char from the start_included where this argument is included in the return and the counter_included where this argument is also included in the return. Similar to slice method but slice does not include the second argument index.

substring(start_index, end_index)

almost completely the same as the above method but the end_index is not included it is end_index-1 which is included and between this interval the string is returned.

common method

toLowerCase()

changes the full string to lower case letters no matter what the letters are currently in the string that is being affected.

toUpperCase()

changes the full string to upper case letters no matter what the letters are currently in the string that is being affected.

toString()

converts the data to string so that strings methods can be applied to it.

common method

trim()

removes both spaces at the end and the beginning of a string

Quick reference (basic methods):

-charAt(index)
-charCodeAt(index)
-concat(params)
-fromCharCode(unicode_num_integer)
-indexOf(string_char)
-lastIndexOf(char)
-replace(to_be_replaced,put_instead_of)
-slice(start_index,end_index), goes till end_index-1
-split(criteria)
-substr(start_included,count) includes the char at position start_included and also the count number is included
-substring(start_index,end_index) end_index not included, end_index-1 included in fetching the substring
-toLowerCase()
-toUpperCase()
-toString()
-trim()