NgClasslink

说明link

CSS 类会根据表达式求值结果进行更新，更新逻辑取决于结果的类型：

The CSS classes are updated as follows, depending on the type of the expression evaluation:

• string - 会把列在字符串中的 CSS 类（空格分隔）添加进来，

  string - the CSS classes listed in the string (space delimited) are added,

• Array - 会把数组中的各个元素作为 CSS 类添加进来，

  Array - the CSS classes declared as Array elements are added,

• Object - 每个 key 都是要处理的 CSS 类，当表达式求值为真的时候则添加，为假则移除。

  Object - keys are CSS classes that get added when the expression given in the value evaluates to a truthy value, otherwise they are removed.

      
        content_copy
      
      <some-element [ngClass]="'first second'">...</some-element>

<some-element [ngClass]="['first', 'second']">...</some-element>

<some-element [ngClass]="{'first': true, 'second': true, 'third': false}">...</some-element>

<some-element [ngClass]="stringExp|arrayExp|objExp">...</some-element>

<some-element [ngClass]="{'class1 class2 class3' : true}">...</some-element>