v2.0.1 Fix size calculation by checking sign

Fix size calculation by checking sign

v2.0.0 migrate to typescript

• migrate to typescript

v.1.0.15

Allow size string usage and make more declarative

Reltade PR

• #17

v.1.0.14

• remove useless console.log

v.1.0.9

• make bundle with rollup
• make bundle file with cjs format

v.1.0.11

• bundle format with umd

v.1.0.10

• add npmignore

v.1.0.8

Descriptions:

• add set flexible breakpoints
• add get breakpoints
• update index.d.ts