Differences between = = and = = = in JS (detailed explanation)

Simply speaking ：== It means the same ,=== The representation is strictly the same , Why do you say that

I understand that ： When making a double equal sign comparison ： First check the two operands data types , If the same , Is to === Compare , If different , Is willing to do a type conversion for you , Convert to the same type and then compare , and === When comparing , If the type is different , Is directly false.

Operands 1 == Operands 2,   Operands 1 === Operands 2

Comparison process ：

Double equal sign ==：

（1） If the two value types are the same , Three more equal signs (===) Comparison

（2） If the two value types are different , It could be the same , The following rules are needed for type conversion in comparison ：

    1） If one is null, One is undefined, So equal

    2） If one is a string , One is numerical value , Convert the string to a numeric value before comparing

Three equal signs ===：

（1） If the type is different , It must not be equal

（2） If both are numerical , And it's the same value , So equal ; If at least one of them is NaN, So it's not equal .（ Judge whether a value is NaN, Only use isNaN() To judge ）

（3） If both are strings , The characters in each position are the same , So equal , Otherwise it's not equal .

（4） If both values are true, or false, So equal

（5） If both values refer to the same object or function , So equal , Otherwise it's not equal

（6） If both values are null, or undefined, So equal