javascript - 如何检查数组中是否存在字符串？

Question

var colors = ["blue", "cyan", "gold", "grey", "orange", "red"];
var gussess = 0;
var color_choosed;
var color_guessed;

function game() {
    color_choosed = "grey";
    color_guessed = prompt("I'm thinking of one of these colors");
    if (colors.indexOf(color_guessed) > colors.indexOf(color_choosed))
        alert("The color choosed is after my color");
    else if (colors.indexOf(color_guessed) < colors.indexOf(color_choosed))
        alert("The coloris befor my color");
    else if (colors.indexOf(color_guessed) == colors.indexOf(color_choosed))
        alert("congrats you are right my color is " + color_guessed);
    else if (color_guessed not in colors)
        alert("The color is not in the list");
}

我想编写一个 if 语句来检查用户是否放置了不在列表中的颜色..做些什么？提醒他该颜色不在列表中

Answer 1

I want to write an if statement to check if the user has put a color not in the list ..

这是if语句，您可以使用它来检查用户的输入是否在您的数组中:

if(colors.indexOf(color_guessed) === -1) { // code here }

重要通知: indexOf() 如果数组中不存在该值，则返回-1。这会给您的代码带来一些额外的副作用。 为了解决这个问题，您应该将最后一个 if 语句移到开头，使其成为第一个语句，如下所示:

function game() {
    color_choosed = "grey";
    color_guessed = prompt("I'm thinking of one of these colors");
    if(colors.indexOf(color_guessed) === -1) // color not found in array
        alert("The color is not in the list");
    else if (colors.indexOf(color_guessed) > colors.indexOf(color_choosed)) // color is after
        alert("The color choosed is after my color");
    else if (colors.indexOf(color_guessed) < colors.indexOf(color_choosed)) // color is before
        alert("The coloris befor my color");
    else if (color_guessed === color_choosed) // colors match!
        alert("congrats you are right my color is " + color_guessed);
}