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for循环中函数回调的返回值

reselect javascript

1

Aessandro · 技术社区 · 6 年前

我有以下for循环:

import { createSelector } from 'reselect';

let dirtyForm;

export const isFormDirty = createSelector(
    getForms,
    getState,
    (forms, state) => {
        for(let i = 0; i < forms.length; i += 1){
            dirtyForm = isDirty(forms[i])(state);
        }

        return dirtyForm;
    }
);

它可以工作,但是在这种情况下有没有一种方法不必使用for循环呢?

3 回复 | 直到 6 年前

1

5

mehmetseckin 6 年前

最后一个窗体的状态将始终覆盖循环中的其他窗体。

如果你想知道任何其中一张表格很脏,你可以用 Array.prototype.some()

export const isFormDirty = createSelector(
    getForms,
    getState,
    (forms, state) => forms.some(form => isDirty(form)(state)) // Will return true if one of the forms are dirty, false if all forms are clean
);

或者,正如@Danmoreng在注释中所建议的,您可以保留循环,并通过添加或“使用dirtyForm标志本身”来防止重写:

for (let i = 0; i < forms.length; i += 1) {

    // Once true, further results will not be evaluated, so no overrides
    dirtyForm = dirtyForm || isDirty(forms[i])(state);
}

for (let i = 0; i < forms.length; i += 1) {

    // Exit the loop by returning true if a form is dirty
    // Might be wise to add a "return false;" outside the loop with this approach.
    if(isDirty(forms[i])(state)) {
        return true;
    }
}

2

0

Jolleyboy 6 年前

export const isFormDirty = createSelector(
    getForms,
    getState,
    (forms, state) => forms.some(form => isDirty(form)(state))
);

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3

0

Justin 6 年前

使用 Array.some()