即使單擊 - ÷ * ，我也無法理解為什么會收到錯誤訊息（默認情況）？是不是應該像我在switch case中定義的那樣設定狀態？我認為它會設定狀態
這是我的代碼，請告訴我我做錯了什么？？
class App extends React.Component {
constructor(props){
super(props);
this.state={
num:[],
sign:"",
res:0
}
this.handleclick=this.handleclick.bind(this);
this.handelAssign=this.handelAssign.bind(this);
}
handleclick(ele) {
this.setState({ num: [...this.state.num, ele] });
this.handelAssign(ele);
};
handelAssign = (operator) => {
/**operatior could be - * ÷ */
switch (operator) {
case operator === " ":
this.setState({ operator: " " });
break;
case operator === "-":
this.setState({ operator: "-" });
break;
case operator === '*':
this.setState({ operator: "*" });
break;
case operator === "÷":
this.setState({ operator: "/" });
break;
default:
throw new Error('sorry you must enter a valid operator')
}};
render() {
const buttons = ["÷", 1, 2, 3, "*", 4, 5, 6," ", 7, 8, 9, ".", 0, "-"];
let allbuttons="";
return (
<div className="calculation-grid">
<div className="output">
<div className="previous-operand">{this.state.num}</div>
<div className="current-operand"></div>
</div>
<button className="span-two">AC</button>
<button>DEL</button>
{allbuttons=buttons.map((ele)=><button onClick={()=>this.handleclick(ele) } key={ele}>{ele}</button>)}
<button className="span-two">=</button>
</div>
);
}
}
uj5u.com熱心網友回復：
你可以試試這個：
handelAssign = (operator) => {
/**operatior could be - * ÷ */
switch (operator) {
case " ":
this.setState({ operator: " " });
break;
case "-":
this.setState({ operator: "-" });
break;
case '*':
this.setState({ operator: "*" });
break;
case "÷":
this.setState({ operator: "/" });
break;
default:
throw new Error('sorry you must enter a valid operator')
}};
uj5u.com熱心網友回復：
嘗試從 swtich 案例中洗掉條件
handelAssign = (operator) => {
/**operatior could be - * ÷ */
switch (operator) {
case " ":
this.setState({ operator: " " });
break;
case "-":
this.setState({ operator: "-" });
break;
case "*":
this.setState({ operator: "*" });
break;
case "÷":
this.setState({ operator: "/" });
break;
default:
throw new Error('sorry you must enter a valid operator')
}};
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