我搜索了所有可能的方法,但我无法弄清楚如何组合返回类型注释和胖箭头语法.
class BasicCalculator{
value:number;
constructor(value:number=0){
this.value=value;
}
add= (operand:number)=>{ // CAVEAT how to add return type???
this.value+=operand;
return this;
}
subtract= (operand:number)=>{
this.value-=operand;
return this;
}
multiply= (operand:number)=>{
this.value*=operand;
return this;
}
divide= (operand:number)=>{
this.value/=operand;
return this;
}
}
我试过了:
add= (operand:number)=>number { ....
但它不起作用.
你可以写:
class BasicCalculator{
value:number;
constructor(value:number=0){
this.value=value;
}
add = (operand:number):BasicCalculator =>{
this.value+=operand;
return this;
}
subtract= (operand:number)=>{
this.value-=operand;
return this;
}
multiply= (operand:number)=>{
this.value*=operand;
return this;
}
divide= (operand:number)=>{
this.value/=operand;
return this;
}
}
let test = new BasicCalculator();
test.add(5);
但即使您没有为add函数编写返回类型,TypeScript也可以在这种情况下推断出类型.您可以add在操场上使用CTRL 将鼠标悬停在该功能上.
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