Question

如何在此对象/数组中搜索获取字段名称的第一个元素？

在此示例中，如果我要搜索second

，我需要获取#999999

colors = { 
    first: ['#cccccc', '#999999'],
    second: ['#999999', '#626262'],
    third: ['#eeeeee', '#afafaf']
};

我试过这样的事情：

for(var field in colors) {
    if(colors.hasOwnProperty(field)) {
        if(colors[field] === '#999999') {
            console.log(field); // gives 'second'
            var color1 = colors[field][0],
                color2 = colors[field][1];
        }
    }
}

也许这会更简化。

Answer 1

尝试使用Object.keys()，Array.prototype.filter();返回"#999999"位于数组<{p>}的索引0的对象的属性名称

＆＃13;

var colors = {
  first: ['#cccccc', '#999999'],
  second: ['#999999', '#626262'],
  third: ['#eeeeee', '#afafaf']
};

var n = "#999999";

var res = Object.keys(colors).filter(function(key, index) {
  return colors[key][0] === n
});

console.log(res[0])

＆＃13;

Answer 2

colors[field]是整个数组。你忘了测试Array元素。你的循环看起来应该更像：

for(var field in colors){
  if(colors[field][0] === '#999999'){
    console.log(field); // gives 'second'
  }
}

Answer 3

如果要在该阵列位置找到该搜索参数的所有键名，请使用数组捕获它们。这是一个通用函数来解决这个问题，以防你在那个位置有多个具有该参数的数组。

var canvas = <HTMLCanvasElement>document.getElementById('myCanvas');
var context = canvas.getContext("2d");
var img = new Image();
img.onload = function () {
    context.drawImage(img, 0, 0);
}
img.src = "zombie.png";

var mapArray =
       ["############################",
        "#      #    #      o      ##",
        "#                          #",
        "#   ####   #####    ##     #",
        "##         #   #    ##     #",
        "###           ##     #     #",
        "#           ###      #     #",
        "#   ####          ###      #",
        "#   ##    #  o             #",
        "# o  #    #    o ###   ### #",
        "#    #    #                #",
        "############################"];

//need to add wall.scource =  and grass.source =
var wall = new Image();
var grass = new Image();
grass.src = "http://vignette2.wikia.nocookie.net/tibia/images/6/60/Grass_(Tile).gif/revision/latest?cb=20080817072800&path-prefix=en";
wall.src = "https://s-media-cache-ak0.pinimg.com/236x/74/37/22/74372202cfd397f5fbd004fc45d83ca3.jpg";

var posX = 0;
var posY = 0;

context.rect(posX, posY, 50, 50)
context.stroke();//traces path, might not need this


function move(e) {
    alert(e.keycode);//gives feedback to what each keydcode is, but doesn't work
    if (e.keycode == 39) {
        posX += 5;
    }
    if (e.keycode == 37) {
        posY += 5;
    }
    canvas.width = canvas.width;
    context.rect(posX, posY, 50, 50)
    context.stroke();
}


    document.onkeydown = move;

DEMO

在对象中搜索数组的第一个元素以获取字段名称

3 个答案: