9 powerful mainstream writing methods in JS (various Hack writing methods)

1. Global replacement

We know that the string function replace () only replaces the first occurrence Condition.

You can replace all occurrences by adding /g at the end of the regular expression.

var example = "potato potato";
console.log(example.replace(/pot/, "tom")); 
// "tomato potato"
console.log(example.replace(/pot/g, "tom")); 
// "tomato tomato"

2. Extract unique values

By using the Set object and the spread operator, we can create a new array with only unique values.

var entries = [1, 2, 2, 3, 4, 5, 6, 6, 7, 7, 8, 4, 2, 1]
var unique_entries = [...new Set(entries)];
console.log(unique_entries);
// [1, 2, 3, 4, 5, 6, 7, 8]

3. Convert number to string

We just need to connect a set of empty quotes.

var converted_number = 5 + "";
console.log(converted_number);
// 5
console.log(typeof converted_number); 
// string

4. Convert string to number

All we need is operator.

One thing to note is that it only applies to "string numbers".

the_string = "123";
console.log(+the_string);
// 123
the_string = "hello";
console.log(+the_string);
// NaN

5. Randomly arrange the elements in the array

I shuffle the cards every day

var my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9];
console.log(my_list.sort(function() {
    return Math.random() - 0.5
})); 
// [4, 8, 2, 9, 1, 3, 6, 5, 7]

6. Multidimensional array flattening

Just use the spread operator.

var entries = [1, [2, 5], [6, 7], 9];
var flat_entries = [].concat(...entries); 
// [1, 2, 5, 6, 7, 9]

7. Short Circuit Condition

Let’s look at this example:

if (available) {
    addToCart();
}

Just use a variable with a function to shorten it ：

available && addToCart()

8. Dynamic property names

I always thought that I must first declare an object before assigning dynamic properties.

const dynamic = 'flavour';
var item = {
    name: 'Coke',
    [dynamic]: 'Cherry'
}
console.log(item); 
// { name: "Coke", flavour: "Cherry" }

9. Use length to adjust or clear an array

We mainly rewrite the length of the array.

If we want to adjust the size of the array:

var entries = [1, 2, 3, 4, 5, 6, 7];  
console.log(entries.length); 
// 7  
entries.length = 4;  
console.log(entries.length); 
// 4  
console.log(entries); 
// [1, 2, 3, 4]

If we want an empty array:

var entries = [1, 2, 3, 4, 5, 6, 7]; 
console.log(entries.length); 
// 7  
entries.length = 0;   
console.log(entries.length); 
// 0 
console.log(entries); 
// []

Recommended tutorial: "JS Tutorial"

The above is the detailed content of 9 powerful mainstream writing methods in JS (various Hack writing methods). For more information, please follow other related articles on the PHP Chinese website!