Math.round() round literally means "nearby around"
The first digit after the decimal point <5
Positive number: Math.round(11.46)=11
Negative numbers: Math.round(-11.46)=-11
The first digit after the decimal point>5
Positive number: Math.round(11.68)=12
Negative numbers: Math.round(-11.68)=-12
The first digit after the decimal point=5
Positive number: Math.round(11.5)=12
Negative numbers: Math.round(-11.5)=-11
Summary: Rounding up
2. Math.ceil(): According to the literal meaning of "ceil" "ceil" to understand;
For example:
Math.ceil(11.46)=Math.ceil(11.68)=Math.ceil(11.5)=12
Math.ceil(-11.46)=Math.ceil(-11.68)=Math.ceil(-11.5)=-11
Summary: round up
3.Math.floor(): understand according to the literal meaning of "floor";
For example:
Math.floor(11.46)=Math.floor(11.68)=Math.floor(11.5)=11
Math.floor(-11.46)=Math.floor(-11.68)=Math.floor(-11.5)=-12
Summary: round down