1. Replace all

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

You can replace all occurrences by adding /g to 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"Copy the code

2. Extract unique values

By using the Set object and the expansion operator, we can create a new array with 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]Copy the code

3. Convert numbers to strings

We just need to use the concatenation operator with empty quotes.

var converted_number = 5 + ""; console.log(converted_number); // 5 console.log(typeof converted_number); // stringCopy the code

4. Convert strings to numbers

All we need is the + operator.

Note that it only applies to “string numbers”.

the_string = "123"; console.log(+the_string); // 123 the_string = "hello"; console.log(+the_string); // NaNCopy the code

5. Arrange the elements of the array randomly

I do it 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]Copy the code

Flatten a two-dimensional array

Just use the expansion operator.

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

7. Shorten conditional statements

Let’s look at this example:

if (available) {
    addToCart();
}
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Shorten it by simply using variables and functions:

available && addToCart()
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8. Dynamic property names

I always thought you had to declare an object before you could assign dynamic properties.

const dynamic = 'flavour';
var item = {
    name: 'Coke',
    [dynamic]: 'Cherry'
}
console.log(item);
 // { name: "Coke", flavour: "Cherry" }
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Use length to adjust/empty the array

We basically overwrite the length of the array.

If we want to resize 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]
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If we want to empty the 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); / / []Copy the code

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