JS Basic knowledge

1. JS Data type: Primitive type (number, String, Boolean, null,undefined), object type (date, regular, array, function ).

2, the string in JS is immutable. Arrays and objects are variable.

3, JS in the variable when there is no type, with VAR declaration. A variable can be given a different value.

4, JS in infinity with infinity-infinity expression.

5, JS does not distinguish between shaping and floating-point type, are based on floating-point type calculation.

6, the arithmetic operation in JS. Math.pow round min max sqrt sin log ceil floor abs PI E exp () Radom

7, Math.Round ()//rounding Math.ceil ()//up to the whole Math.floor ()//down to the whole

JS Basic knowledge