Question

我有一系列的部分。使用向上和向下箭头键，我想得到当前和下一个值，不要循环，如下所示。

var sections = [ "A", "B","C","D"];

$(document).keydown(function(e){

    var k= e.which;

    if(k==40){ sections.push( sections.shift() ); }

    else if(k==38){ sections.unshift( sections.pop() ); }

    $('body').html( 'You just went to ' + sections[0] ); // current section.
    // How to return the previous section that I was in?
    // For example: You just left section A then went to section B
    // Do not loop, return: You just reached end/beginning
});

工作小提琴：http://jsfiddle.net/9977ov2x/

Answer 1

var sections = [ "A", "B","C","D"];
var i=0;
$(document).keydown(function(e){

    var k= e.which;

    if(k==40){ i++; }

    else if(k==38){ i--; }

    if(i>=sections.length){
    i=0;
    }
    else if(i<0)
    {
    i=sections.length-1;
    }

    $('body').html( 'You just went to ' + sections[i] ); // return the current section.
    // How to return the previous section?
    // For example: You just left section A then went to section B
    // Also stop if I'm at the end or begaing then return: You just rech end/beginig
});

http://jsfiddle.net/9977ov2x/2/

Answer 2

试试吧

var sections = ["A", "B", "C", "D"];
var i = 0;
var $pre = $('p');
var $now = $('span');
var $next = $('div');
$(document).keydown(function (e) {

    var k = e.which;
    var pretmp = sections[i] ;
    //Next is same to it you put the variables to the if block below and then echo 2 line in some html tag " if press up will be " and " else will be " so you will have 2 next tmp var i assume it next1 and next2
    if (k == 40) {
        i++;   
        // next1
    } else if (k == 38) {

        i--;
        //next2
    }

    if (i >= sections.length) {
        i = 0;
    } else if (i < 0) {
        i = sections.length - 1;
    }
    $pre.html('Previous is ' + pretmp);
    $now.html('You just went to ' + sections[i]); // return the current section.
    // How to return the previous section?
    // For example: You just left section A then went to section B
    // Also stop if I'm at the end or begaing then return: You just rech end/beginig
});

和身体中的html

<p></p><span></span><br/><div></div>

jQuery - 向上和向下键从数组中获取值

2 个答案: