[英]Why is only my last object being updated in loop in object
I have two objects, One is an array that looks like this:我有两个对象,一个是一个看起来像这样的数组:
let value = [123,500];
The other is an array of objects that looks like this:另一个是一个看起来像这样的对象数组:
let mapObject = [
{id:123,name:"Thing 1"},
{id:444,name:"Thing 2"},
{id:500,name:"Thing 3"},
{id:777,name:"Thing 4"}
];
The goal of the next function is to iterate over the mapObject and if the id matches any of the elements in the value, then set a new property called 'on' to true, otherwise set it to false. next 函数的目标是迭代 mapObject,如果 id 与值中的任何元素匹配,则将名为“on”的新属性设置为 true,否则将其设置为 false。 Here is the code for that:
这是代码:
for (let i in mapObject) {
for (let j in value) {
if (mapObject[i].id == value[j]) {
mapObject[i].on = true;
} else {
mapObject[i].on = false;
}
}
}
What I expect is this:我期望的是:
[
{id:123,name:"Thing 1",on:true},
{id:444,name:"Thing 2",on:false},
{id:500,name:"Thing 3",on:true},
{id:777,name:"Thing 4",on:false}
]
However what I am actually getting it this:然而,我实际上得到的是这样的:
[
{id:123,name:"Thing 1",on:false},
{id:444,name:"Thing 2",on:false},
{id:500,name:"Thing 3",on:true},
{id:777,name:"Thing 4",on:false}
]
Why does this happen?为什么会发生这种情况?
Your loop logic is not good.你的循环逻辑不好。 Once you update the value to true you should break from the inner loop.
将值更新为 true 后,您应该中断内部循环。
for (let i in mapObject) {
for (let j in value) {
if (mapObject[i].id == value[j]) {
mapObject[i].on = true;
break;
} else {
mapObject[i].on = false;
}
}
}
The problem is that once you update the value to true
you loop again with the same mapObject[i].id
and test it against a new value from value[j]
.问题是,一旦您将值更新为
true
您将再次使用相同的mapObject[i].id
循环,并针对value[j]
中的新值对其进行测试。
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