javascript - 变量通过 Javascript 函数返回

Question

我的 javascript 有问题，每当我将数组发送到另一个函数(通过参数)进行使用和格式化时，它都会以某种方式将格式化的数组返回到前​​一个函数。

https://jsfiddle.net/jvrqt0mg/1/

HTML

<p>Column</p>
<select id='colSelect'></select>
<p>Weight</p>
<select id='weightSelect'></select>

JavaScript

updateTableSettings = function () {
var colAmount = "4";
var colArray = [];

//Updates the array with the dropdown options selected by the user
updateDropdown = function (notWeight) {

    //Gets the max amount of weight (The row amount)
    var colWeight = colAmount;
    var colAmount2 = colAmount;

    //Minuses the number selected in the column drop down with weight. 
    colWeight = colWeight - ($("#colSelect option:selected").text() - 1);
    colAmount2 = colAmount2 - ($("#weightSelect option:selected").text() - 1);

    //Checks to make sure that it was the column that changed and not the weight drop down
    colArray[($("#colSelect option:selected").text()) - 1] = (eval($("#weightSelect option:selected").text()) - 1);

    //Resets the weight drop down
    $("#weightSelect").find("Option").remove().end();
    //Repopulates the weight drop down depending on how much weight is left
    for (var i = 0; i < colWeight; i++) {
        //Creates a new option in the weight drop down
        $("#weightSelect").append(new Option(i + 1, (i + 1)));
    }




    //This is me passing the array whenever a drop down has been selected or changed
    //Sends it to the array to the new function(I want dont want the array in function to be formatted)
    format(colArray);



    //This shows the array in this function getting formatted
    console.log(colArray);
    return;
};

//Fills the array       
var fillArray = function () {
    for (var i = 0; i < colAmount; i++) {
        colArray[i] = 0;
    }
};

//Removes all the options to make sure they don't double up
$("#colSelect").find("Option").remove().end();
$("#weightSelect").find("Option").remove().end();

//Populates the array
fillArray();
//Creates the options in the drop down
for (var i = 0; i < colAmount; i++) {
    //Gives the colArray a default of 0 for every column
    $("#weightSelect").append(new Option(i + 1, ("weight" + i)));

    $("#colSelect").append(new Option(i + 1, ("opt" + i)));
}
//Checks column drop down for a change
this.$("#colSelect, #weightSelect").change(function (e) {
    updateDropdown();
});
};



//This is where the array gets passed into
format = function (array) {
//Formats so it pops the array for every value inside the array
formatArray = function (array) {
    var testArray = [];
    testArray = array;
    for (var i = 0; i < array.length; i++) {
        for (var k = 0; k < array[i]; k++) {



            //This seems to delete the array in a different function... HOW?~?!!!
            testArray.pop();



        }
    }
    return;
};
//alert this
formatArray(array);
//I will have code to draw a table row with columns/weight(Size)
};

我希望原始数组保持不变，因此每次更改下拉列表时都会重新发送数组。

抱歉我的代码不好，我是 JS 新手。 提前致谢

Answer 1

在将数组传递给函数之前，使用 slice() 对其进行复制:

var array = [1, 2, 3, 4];
// makes a copy
var arrayCpy = array.slice(); 
// works with copy and your original array stays intact 
someFunction(arrayCpy); 

这是因为数组是通过引用传递的，而不是值。参见 fiddle :http://jsfiddle.net/2tfeLenL/

另外:http://orizens.com/wp/topics/javascript-arrays-passing-by-reference-or-by-value/