盡管（鍵，值）對已定義，但Javascript Map返回未定義

Question

我正在使用nodejs在linux終端中運行此代碼段。 盡管正確設置了（鍵，值）對，但是代碼未定義打印。 任何解釋或解決此問題？

function trial() {
    var obj1 = {};
    var obj2 = {};
    obj1.fund = 1;
    obj1.target = 2;
    obj2.fund = 1;
    obj2.target = 2;
    states = [];
    states.push(obj1);
    states.push(obj2);
    actions = [1,2,3,4];
    table = new Map();
    for (var state of states) {
        for (var action of actions) {
            cell = {};
            cell.state = state;
            cell.action = action;
            table.set(cell, 0);
        }
    }
    var obj = {};
    obj.state = states[1];
    obj.action = actions[1];
    console.log(table.get(obj));   
}

Answer 1

您需要原始的對象引用來匹配table（ Map() ）中的鍵，讓我們保存每個新的cell ，每個cell就是顯示該對象的引用。

甚至您對Map()都有很深的對象克隆，它也不是相同的鍵。

  var obj1 = {}; var obj2 = {}; obj1.fund = 1; obj1.target = 2; obj2.fund = 1; obj2.target = 2; states = []; states.push(obj1); states.push(obj2); actions = [1,2,3,4]; table = new Map(); var objRefs = []; var count = 0; for (var state of states) { for (var action of actions) { cell = {}; cell.state = state; cell.action = action; table.set(cell, count); objRefs.push(cell); //hold the object reference count ++; } } for (var i = 0; i < objRefs.length; i++) { console.log(table.get(objRefs[i])); } // Copy by reference var pointerToSecondObj = objRefs[1]; console.log(table.get(pointerToSecondObj)); //Deep clone the object var deepCloneSecondObj = JSON.parse(JSON.stringify(objRefs[1])); console.log(table.get(deepCloneSecondObj)); 

Answer 2

試試這個。 您可能會得到所需的東西。 我做了一個小小的美化。

function trial() {
    var obj1 = {
            fund: 1,
            target: 2
        },
        obj2 = { 
            fund: 1,
            target: 2
        },
        obj = {},
        states = [
            obj1, obj2
        ],
        actions = [1,2,3,4],
        table = new Map(),
        cell
    ;
    for (var state of states) {
        for (var action of actions) {
            cell = {};
            cell.state = state;
            cell.action = action;
            table.set(cell, 0);   
        }
    }
    obj.state = states[1];
    obj.action = actions[1];
    return(obj);
    //console.log(table.get(obj));   
}
console.log(trial())