Question

我将随机背景颜色（从3个调色板）应用到页面的不同部分。但是，我想确保相同的颜色不会连续出现两次。

我认为一个小do while循环可以正常工作，但它看起来并不完全。

var colours = new Array('#FF5A5A', '#FFBE0D', '#00DDB8');    

var divs = $('.row');
var last;
var next;

// for each section
divs.each(function(i){

    // get a random colour
    do {

        next = Math.floor(Math.random()*3);

        // if it's the same as the last one, try again!
        } while( next === last ) {

            next = Math.floor(Math.random()*3);

        }

        // when it's different to the last one, set it
        $(this).css('background-color', colours[next] );

        // tell it this is the last one now
        next = last;

});

有什么想法吗？

Answer 1

这是一种语法错误 - 你无法决定你是想要一个do-while-loop还是一个普通的while循环？你把它放在那里将被解释为一个简单的block：

do {
    next = Math.floor(Math.random()*3);
} while( next === last ) // end of the do-while-loop!
// Block here - the braces could be omitted as well:
{
    next = Math.floor(Math.random()*3);
}
$(this).css('background-color', colours[next] );
…

这将正确计算与最后一个不同的数字，但随后它将使用新的（不受限制的）随机数覆盖它。此外，作业next = last;与你想要的完全相反。

所以将脚本更改为

do {
    next = Math.floor(Math.random()*3);
} while( next === last ) // if it's the same as the last one, try again!

// tell it this is the last one now
last = next;

// now that we've made sure it's different from the last one, set it
$(this).css('background-color', colours[next] );

Answer 2

修订 - （因为我感受到了挑战！）http://jsfiddle.net/6vXZH/2/

var last, colours = ['#ff5a5a', '#ffbe0d', '#00ddb8'];    

$('.row').each(function() {
  var color = colours.splice(~~(Math.random()*colours.length), 1)[0];
  $(this).css('background-color', color);   
  last && colours.push(last), last = color;
});

希望这有帮助！如果您愿意的话，我很乐意为您提供游戏。

使用小数组魔法，无需内循环（http://jsfiddle.net/6vXZH/1/） -

var colours = ['#ff5a5a', '#ffbe0d', '#00ddb8'];    
var used = [];

// for each section
$('.row').each(function(i){

  var color = colours.splice(~~(Math.random()*colours.length), 1)[0];
  $(this).css('background-color', color);

  used.push(color);

  if(used.length > 1) {
    colours.push(used.shift());
  }
});

Answer 3

在函数更好之前定义next和last。

var next=last=Math.floor(Math.random()*3);

$divs.each(function(i){        
    do {
        next = Math.floor(Math.random()*3);
    } while( next === last );  
    $(this).css('background-color', colours[next] );
    next = last;
});

Answer 4

{
var colours     = ['#FF5A5A', '#FFBE0D', '#00DDB8'],
    divs        = $('.row'),
    coloursSize = colours.length,
    last,
    next;


divs.each(function(i){

// get a random colour
    do {
            next = Math.floor( Math.random() * coloursSize );
            // if it's the same as the last one, try again!
        } while( next === last ) 
        // when it's different to the last one, set it
        $(this).css('background-color', colours[next] );
        // tell it this is the last one now
        last = next;

});

}

jQuery随机数组编号与上一个不同

4 个答案: