JS 一些注意事項

1對象引用，對象賦值

此圖中遍歷導致被遍歷的值發生改變

後來這麼改了，原來被遍歷的list便不會被影響：

let newCategoryTabs = [];

for (var i = 0; i < categoryTabsDefault.length; i++) {
    let newPlProds = [];
    let item = categoryTabsDefault[i];
    console.log("item---i--->" + i + "-->" + JSON.stringify(item));
    for (var j = 0; j < item.plProds.length; j++) {
        let item2 = item.plProds[j];
        console.log("item--->" + JSON.stringify(item2));
        let isThisRecord = false;
        if ((item2.plProduct.CPQ_Product__r.Internal_Model__c.indexOf(searchListItem) != -1) && (item2.plProduct.CPQ_Product__r.Internal_Model__c != undefined) && isThisRecord == false) {
            newPlProds.push(item2);
            isThisRecord = true;
        } else if (isThisRecord == false && (item2.plProduct.CPQ_Product__r.External_Model__c != undefined) && (item2.plProduct.CPQ_Product__r.External_Model__c.indexOf(searchListItem) != -1)) {
            newPlProds.push(item2);
            isThisRecord = true;
        } else if (isThisRecord == false && (item2.plProduct.CPQ_Product__r.Part_No__c != undefined) && (item2.plProduct.CPQ_Product__r.Part_No__c.indexOf(searchListItem) != -1)) {
            newPlProds.push(item2);
            isThisRecord = true;
        } else if (isThisRecord == false && (item2.plProduct.CPQ_Product__r.Product_Name__c != undefined) && (item2.plProduct.CPQ_Product__r.Product_Name__c.indexOf(searchListItem) != -1)) {
            newPlProds.push(item2);
            isThisRecord = true;
        }
    }
    //item.plProds = newPlProds;
    //因爲對象的簡單和深度克隆（賦值與引用的區別），如果向上面一樣直接=會改變categoryTabsDefault的值，所以新建一個對象防止引用賦值導致遍歷的list的值發生改變
    let newItem=new Object();
    newItem.id=item.id;
    newItem.name=item.name;
    newItem.plProds=newPlProds;
    console.log("newItem---》"+JSON.stringify(newItem));
    newCategoryTabs.push(newItem);
}
console.log("newCategoryTabs--333->" + JSON.stringify(newCategoryTabs));
console.log("categoryTabsDefault--22222->" + JSON.stringify(categoryTabsDefault));

 

具體需要去了解一下JS對象簡單、深度克隆(賦值與引用的區別)

參考：https://blog.csdn.net/pugongyingyangyue/article/details/74928646

 

 

以下使用es6的語法改寫：

 let newCategoryTabs = categoryTabsDefault.reduce((prev, item) => {
     let newPlProds = item.plProds.reduce((prev2, item2) => {
         let isThisRecord = false;
         if ((item2.plProduct.CPQ_Product__r.Internal_Model__c.indexOf(searchListItem) != -1) && (item2.plProduct.CPQ_Product__r.Internal_Model__c != undefined) && isThisRecord == false) {
             prev2.push(item2);
             isThisRecord = true;
         } else if (isThisRecord == false && (item2.plProduct.CPQ_Product__r.External_Model__c != undefined) && (item2.plProduct.CPQ_Product__r.External_Model__c.indexOf(searchListItem) != -1)) {
             prev2.push(item2);
             isThisRecord = true;
         } else if (isThisRecord == false && (item2.plProduct.CPQ_Product__r.Part_No__c != undefined) && (item2.plProduct.CPQ_Product__r.Part_No__c.indexOf(searchListItem) != -1)) {
             prev2.push(item2);
             isThisRecord = true;
         } else if (isThisRecord == false && (item2.plProduct.CPQ_Product__r.Product_Name__c != undefined) && (item2.plProduct.CPQ_Product__r.Product_Name__c.indexOf(searchListItem) != -1)) {
             prev2.push(item2);
             isThisRecord = true;
         }
         return prev2;
     }, []);
     //因爲對象的簡單和深度克隆（賦值與引用的區別），如果向上面一樣直接=會改變categoryTabsDefault的值，所以新建一個對象防止引用賦值導致遍歷的list的值發生改變
    let newItem=new Object();
    newItem.id=item.id;
    newItem.name=item.name;
    newItem.plProds=newPlProds;
    console.log("newItem---》"+JSON.stringify(newItem));
    prev.push(newItem);

     console.log("prev--->" + JSON.stringify(prev));
     return prev;
 }, []);

console.log("newcategoryTabs--->" + JSON.stringify(newCategoryTabs));