10 Things You Didn’t Know About JavaScript (most likely)

Abdullah Al Fahim
2 min readMay 5, 2021

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Learning JavaScript is like swimming on the ocean. One may be in the development field with JavaScript for many years but still there is something he may not know! Today I will share some of them that you may not know.

  1. JavaScript was originally going to be called LiveScript, but it was renamed in an ill-fated marketing decision that attempted to capitalize on the popularity of Java language — despite the two having very little in common. This has been a source of confusion ever since.

2. NaN is not equal to NaN !

NaN === NaN // false

3. You can define Object keys from variable directly:

Cont firstProperty = “name”;Const myObj = {[firstProperty]: “Hasan”,}

4. The length property of Array is not always the number of items the array contains.

For instance:

Remember, the length of an array is one more than the highest index.

5. If you use expressions in switch statements it won’t convert implicitly. It will act like === operator.

6. Empty string(“”) is treated as falsy value but empty array([]) and empty object({}) are treated as truthy value.

Boolean("") // falseBoolean([]) // true

Consider this:

Const a = {} || 5; // a={}Const a = “” || 5; // a=5

If you want to use them as truthy value then use array.length or object.property

Boolean([].length) // falseBoolean({}[“name”]) // false

7. String started with “0x” are treated as hexadecimal number.

parseInt(“F”) // NaNparseInt(“0xF”) // 15

8. You can write any character of any language using the escape sequence. Write "\u{XXXXXX}" where XXXX is 1–6 hex digits in the range 010FFFF . e.g. “\u{0985} is “অ”. See the Unicode chart for all the character values.

9. Random function of Math object returns floating point between 0 to 1. But use can get any random number between any two integers using this formula:

function randomBetweenTwo(min, max) {
return Math.floor(Math.random() * (max - min + 1) + min);
}

Though random is not so random!

10. You can create custom properties for Arrays.

const array = [1, 2, 3, 4, 5];
array.type = "numbers";
console.log(array.type); // numbers

That’s it for today. Keep exploring JavaScript.

Peace!

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Abdullah Al Fahim
Abdullah Al Fahim

Written by Abdullah Al Fahim

The more you know, the more you realize you know nothing.

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