charAt(index) - returns the character at index
substring(start, end) - returns string from start to end - 1. if start > end, they are swapped
slice(start, end) - like substring, but without the swapping. instead if start >= end, an empty string is returned
substr(start, count) - returns string from start to start + count
endsWith(str) - returns whether end of string matches str
startsWith(str) - returns whether start of string matches str
includes(str) - returns whether string matches str anywhere
indexOf(str) - returns first index at where str was found
lastIndexOf(str) - returns last index at where str was found
match(regex) - returns regex matches for string (regex is converted to RegEx, if isn't one yet). Wrapper for RegExp.exec.
search(regex) - returns index of first regex match (regex is converted to RegEx, if isn't one yet)
repeat(count) - returns string repeated count times
split(str) - returns array of chunks, split on str
replace(regex/str, str2) - replaces regex/str matches with str2
push(elem) - adds elem to end of array, returns new array length
unshift(elem) - adds elem to beginnging of array, returns new array length
pop() - removes and returns last element in the array
shift() - removes and returns first element in array
splice(start, count, ...elems) - remove count number of elements starting at start, if elems provided, insert them at start
reverse() - reverses the array
fill(elem, start, end) - replace elems with elem from start to end
map(iteratee(el, idx, arr)) - returns a new array with iteratee applied to each element
concat(...elems) - merges array with elems into new array, arrays in elems first unpacked to values
slice(start, end) - returns array from index start to end - 1. if start >= end, an empty array is returned
filter(iteratee(el, idx, arr)) - returns an array composed of all elements for which iteratee returns true
reduce(iteratee(acc, el, idx, arr), startAcc) - returns a value composed of startAcc and running iteratee on each element in array
reduceRight - like reduce but then iterated from end of array to beginning
find(iteratee(el, idx, arr)) - returns the value of the first element in the array that satisfies iteratee. Otherwise undefined
indexOf(elem) - returns first index at where elem was found (using ===)
lastIndexOf(elem) - returns last index at where elem was found (using ===)
every(iteratee(el, idx, arr)) - returns whether iteratee returns true for every element in array
some(iteratee(el, idx, arr)) - returns whether iteratee returns true for any element in array
join(str) - returns string with each elem in array joined by str
includes(elem, start) - find elem in array, if start is undefined or < 0, the entire array is searched
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new RegExp(str, modifiers) -
/str/modifiers
str is a regex which consists of one or more Tokens. modifiers are optional
test(str) - returns whether the regex has any matches in str
exec(str) - search for any matches in str, returns null if no match found. Updates regex object
abc… - Letters
123… - Digits
\d - Any Digit
\D - Any Non-digit character
. - Any Character
\. - Period
[abc] - Only a, b, or c
[^abc] - Not a, b, nor c
[a-z] - Characters a to z
[0-9] - Numbers 0 to 9
\w - Any Alphanumeric character
\W - Any Non-alphanumeric character
{m} - m Repetitions
{m,n} - m to n Repetitions
* - Zero or more repetitions
+ - One or more repetitions
? - Zero or one repetitions
\s - Any Whitespace
\S - Any Non-whitespace character
^…$ - Starts and ends
(…) - Capture Group
(a(bc)) - Capture Group and Sub-group
(abc|def) - Matches abc or def
i - performs case-insensitive matching
g - performs a global match (find all matches rather than stopping after the first match)
m - performs multiline matching
async function foo() {
return 42;
}is syntactic sugar for:
function foo() {
return new Promise(resolve => {
resolve(42);
});
}and this:
const data = await something();
// ...do something...is syntactic sugar for:
something().then(data => {
// ...do something...
});asynckeyword makes a function return a promise which isresolved when the function returnsawaitkeyword waits (locally blocks) for an async function (or promise) to resolve and then replaces the promise with the value it resolved to and continues code execution
More info, see: Tips for using async functions