与对象属性混淆。 我如何不变得“未定义”？

Question

I'm trying to create an array consisting of an object for each letter in the alphabet with two properties. Letter and dd_array. Right now I'm setting dd_array = [] , but I would like it to be the corresponding morseDic property.

So for instance _charObjArray[0] = {letter: 'a', dd_array: [0,1]}

Can I get some tips on how to code this best possible??

alpha_array = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];

morseDic = {
    a: [0,1],
    b: [1,0,0,0],
    c: [1,0,1,0],
    d: [1,0,0],
    e: [0],
    f: [0,0,1,0],
    g: [1,1,0],
    h: [0,0,0,0],
    i: [0,0],
    j: [0,1,1,1],
    k: [1,0,1],
    l: [0,1,0,0],
    m: [1,1],
    n: [1,0],
    o: [1,1,1],
    p: [0,1,1,0],
    q: [1,1,0,1],
    r: [0,1,0],
    s: [0,0,0],
    t: [1],
    u: [0,0,1],
    v: [0,0,0,1],
    w: [0,1,1],
    x: [1,0,0,1],
    y: [1,0,1,1],
    z: [1,1,0,0]
}

function _alpha(_char, dd_array) {
    this.letter = _char;
    this.dd_array = dd_array;
}


var _charObjArray = []
for (i = 0; i < alpha_array.length; i++) {
    var _charNow = alpha_array[i];
    var __charNow = _charNow;
    var __charNow = new _alpha(_charNow, "[]") // "[]" should be replaced with the _charNow corresponding property from morseDic
    _charObjArray.push(__charNow)
}

console.log(_charObjArray);

Answer 1

In _alpha , instead of:

this.dd_array = dd_array;

...you use _char to index into the morseDic object:

this.dd_array = morseDic[_char];

...and then don't pass a second argument to _alpha at all.

But if you want to pass it to _alpha as an argument:

var __charNow = new _alpha(_charNow, morseDic[_charNow]);

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In JavaScript, you can access object properties either with dot notation and a property name literal ( obj.foo , or morseDic.a ), or using brackets notation and a property name string * ( obj["foo"] or morseDic["a"] ). In the latter case, the string can be the result of any expression, including a variable lookup.

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* In ES6, it'll be strings or Symbol s.