javascript React.js setState() 带有用于循环内键的变量？
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React.js setState() with variable for key inside loop?
提问by narwic
Is there a way to use a string variable's value as the key for setState()?
有没有办法使用字符串变量的值作为 setState() 的键？
getInitialState: function () {
return {
foo: '',
bar: ''
}
}
someOtherHandler: function() {
var arr = ['foo', 'bar'];
var _this = this;
var number = Math.random();
for (var i in arr) {
_this.setState({ arr[i]: number });
}
}
React throws a syntax error with the above, and setting arr[i] to a variable ends up setting a new state with that variable's name.
React 会抛出上述语法错误，将 arr[i] 设置为变量最终会使用该变量的名称设置新状态。
回答by Dan Prince
You can create the object before calling setState.
您可以在调用之前创建对象setState。
var newState = {};
newState[i] = number;
_this.setState(newState);
Alternatively if you are using ES6, you could make use of a computed property.
或者，如果您使用的是 ES6，则可以使用计算属性。
_this.setState({ [i]: number });
However this code will call setStatemultiple times, it's more efficient to only call it once. Build the updated state object, then apply it.
但是这段代码会调用setState多次，只调用一次会更有效率。构建更新的状态对象，然后应用它。
var newState = {};
for(var i in arr) {
newState[i] = number;
}
this.setState(newState);
