5-minute mastery of JavaScript tips (from the public, Front end development)

1. Delete the trailing elements of an array

One simple way is to change the length of the array:

Const arr = [one, One, one, one, one, ];

Truncanting

Arr. Length = 3;

Console.  Log(arr); //=> [One, one, one]

Clearing

Arr. Length = 0;

Console.  Log(arr); //=> []

Console.  Log(arr[2]); //=> undefined

2. Using object destructuring to simulate named parameters

If you need to pass in a series of options as arguments into a function, you will most likely use the object to define the configuration (config).

DoSomething({ foo: ' Hello ', bar: ' hey! ') , baz: );

function dosomething(config) {

const foo = config.  Foo !== undefined ? config. Foo : ' Hi ';

Const bar = config.  Bar !== undefined ? config. Bar : ' yo! ' ;

Const baz = config.  Baz !== undefined ? config. Baz : ;

// ...

}

But this is an older approach, which simulates named parameters in JavaScript.

In ES 2015, you can use object deconstruction directly:

function dosomething({ foo = ' Hi ', bar = ' yo! ') , baz = ) {

// ...

}

Making parameters optional is also simple:

function dosomething({ foo = ' Hi ', bar = ' yo! ') , baz = + } = {}) {

// ...

}

3. Using object deconstruction to manipulate arrays

You can use the syntax of an object's deconstruction to get the elements of an array:

Const csvfileline = ' 1997,john doe,us,[email protected],new York ';

Const { 2: country, 4: state } = csvfileline< c23>. split(', ');

4. Using range values in a Switch statement

The statement that satisfies the range value can be written like this:

function getwaterstate(tempincelsius) {

Let state ;

Switch (true) {

case (tempincelsius 0):

state = ' Solid ';

break;

case (tempincelsius > 0 && tempincelsius ):

state = ' Liquid ';

break;

default:

state = ' gas ';

}

return state ;

}

5. Await multiple Async functions

When using async/await, you can use Promise.all to await multiple async functions

Await Promise. All([anasynccall(), thisisalsoasync(), Onemore()])

6. Create a pure objects

You can create a 100% pure object that does not inherit any attributes from object or methods (such as constructor, ToString (), and so on)

Const pureobject = Object. Create(null);

Console.  Log(pureobject); //=> {}

Console. Log(pureobject. constructor); //=> undefined

Console. Log(pureobject. ToString); //=> undefined

Console. Log(pureobject. hasOwnProperty); //=> undefined

7. Formatting JSON Code

Json.stringify can also format the output JSON object in addition to the ability to char an object

Const obj = {

Foo: { bar: [one, one, and] , Baz: { bing: true, boom: ' Hello ' } c42>}

};

The third parameter is the number of spaces used to

Beautify the JSON output.

JSON. Stringify(obj, null, 4);

= = "{

= "Foo": {

= "Bar": [

= 11,

= 22,

= 33,

= 44

=],

= = "Baz": {

= = "Bing": true,

= "Boom": "Hello"

= =}

= =}

=>} "

8. Removing duplicate elements from an array

By using the collection syntax and the Spread operation, it is easy to remove duplicate elements:

Const removeduplicateitems = arr = = [... new Set(arr)];

Removeduplicateitems([a ], ' foo ', a , ' foo' , True, true]);

= = [A, "foo", True]

9. Tiling multidimensional Arrays

To tile nested multidimensional arrays using the Spread operation:

Const arr = [One, [a ] , [] ;

Const Flatarr = []. Concat(... arr); //=> [One, One, one, one, one, and one]

However, the above method only applies to two-dimensional arrays, but with recursion, you can tile arrays of arbitrary dimensions:

function flattenarray(arr) {

Const flattened = []. Concat(... arr);

return flattened. Some(item = Array. IsArray(item)) ?

Flattenarray(flattened) : flattened;

}

Const arr = [One, [a ] , [[n], [[+]] []] ;

Const Flatarr = flattenarray(arr);

= = [11, 22, 33, 44, 55, 66, 77, 88, 99]

5-minute mastery of JavaScript tips (from the public, Front end development)