Math.random(); // [0.0 <= x < 1.0] decimal
Math.floor(3.14156); // 3.0000
Math.ceil(3.14156); // 4.0000
Math.floor(2224565.5616); // 2224565
Math.ceil(2224565.5616); // 2224566
Math.floor(Math.random() * (Max - Min + 1)) + Min; // random num [min < x < max]
Regular Expression
str = "hello world! welcome to programmong."
pattern = /program/gi; // g is global all occurance , i is ignore case
str.match(pattern); // ret 2
Match white space
\r enter return
\n new line
\t tab
\f form feed
" " space
pattern = /\s+/g ; //multi occurance // white space
Match Invert white space
\R not enter return
\N !new line
\T !tab
\F !form feed
str = "hello world!"
pattern = /\S/g; // g is global all occurance
str.match(pattern); // ret 11