Angular 4.x NgClass ngStyle 指令用法

1. <some-element [ngClass]="'first second'">...</some-element>
3. <some-element [ngClass]="['first', 'second']">...</some-element>
5. <some-element [ngClass]="{'first': true, 'second': true, 'third': false}">...</some-element>
7. <some-element [ngClass]="stringExp|arrayExp|objExp">...</some-element>
9. <some-element [ngClass]="{'class1 class2 class3' : true}">...</some-element>

<div [ngStyle]="{'background-color':'green'}"></<div>