Question

任何人都可以告诉我为什么变量current和at不会传递给函数但是当我起诉控制台时出现正确的值？我对这一点完全无能为力，这意味着它必须简单！

records = [118571, 118666, 118693, 118791, 118827, 118942, 119041, 119144, 119265, 119310, 119430, 119570, 119617, 119726, 119762, 120030, 120086, 120103, 120129, 120145, 120219, 120365, 120441, 120562, 120607, 120932, 121072, 121232, 121260, 121667, 121725, 121764, 121876, 122007, 122008, 122009, 122131, 122458, 122804, 123081, 123156, 123239, 123320, 123413, 123624, 123715, 123842, 123953];
x = 48;
y = 48;
current = 123953;
function changerecord(change) {

    var at = records.indexOf(current);

    if (change == -1) {
        var next = current;//current because we are going back one
        var previous = records[at - 3];//-2 because we started on record and are moving 2 back
        var moveto = records[at - 2];
        x = x - 1;
        document.getElementById("count").innerHTML = x + ' of ' + y;
        alert("AT : " + at + "\n" + "Previous : " + previous + "\n" + "Next : " + next + "\n" + "x : " + x + "\n" + "y : " + y + "\n" + "moveto : " + moveto + "\n");
        var current = moveto;
        //document.getElementById('iframe_records').src='recordtemplate.php?flight=' + moveto;
    }
    else if (change == +1) {
        var previous = current;//current because we are going back one
        var next = records[at + 2];//-2 because we started on record and are moving 2 back
        var moveto = records[at + 1];
        x = x + 1;
        alert("AT : " + at + "\n" + "Previous : " + previous + "\n" + "Next : " + next + "\n" + "x : " + x + "\n" + "y : " + y + "\n" + "moveto : " + moveto + "\n");
        document.getElementById("count").innerHTML = x + ' of ' + y;
        var current = moveto;
        //document.getElementById('iframe_records').src='recordtemplate.php?flight=' + moveto;
    }
}; // lookup

Answer 1

你有一些范围和变量名称问题：

首先，尝试使用var

声明变量

var records = [...]
var variable = ...

所以这在当前范围内是全局的，如果函数也在范围内，你也可以在函数中使用它。

您只是更改current的值，而不是在函数范围内，您正在使用var current = ..。使用其他名称，并不是有限的。

var test = 1;

function test() {

    console.log(test); // Output: 1

    var test = 2;
    var oktopus = 8;

    console.log(test); // Output: 2
    console.log(oktopus); // Output: 8

}

console.log(test); // Output: 1
console.log(oktopus); // undefined oktopus

Answer 2

您可以将current作为参数传递，以避免此问题：然后当你拨打changerecord时，它会是这样的：

changerecord(change, 123953)

Answer 3

您已为变量current分配了一个值，但没有使用var关键字声明它。执行此操作时，即为未声明的变量赋值，该变量将成为全局对象（即窗口）上的属性。

您应该知道的另一点是，当您声明一个与父函数作用域中另一个变量同名的局部变量时，最本地化的变量将用于内部函数作用域。

// ...
current = 123953; // Global variable
function changerecord(change) { // Local variable

    var at = records.indexOf(current); // Local variable will be used

    if (change==-1) // Also local one
    {   
        var next = current; // Still local one!
// ...

请注意，window.current应该有效。

Answer 4

尝试：

$(document).ready(function(){
    changerecord(change);
});

javascript变量没有被传递

4 个答案: