Javascript If语句,查看数组

var a = [3,4,5,6,7,8,9];

if ( a.indexOf( 2 ) == -1 ) { 
   // do stuff
}

indexOf 退货 -1 如果找不到号码。它返回的不是 -1

如果需要字符串,请将数字用引号括起来( a = ['1','2']

IE和其他晦涩/旧的浏览器将需要 方法:

if (!Array.prototype.indexOf)  
{  
  Array.prototype.indexOf = function(elt /*, from*/)  
  {  
    var len = this.length >>> 0;  

    var from = Number(arguments[1]) || 0;  
    from = (from < 0)  
         ? Math.ceil(from)  
         : Math.floor(from);  
    if (from < 0)  
      from += len;  

    for (; from < len; from++)  
    {  
      if (from in this &&  
          this[from] === elt)  
        return from;  
    }  
    return -1;  
  };  
}  

我的想法是这样的:

function not(dat, arr) { //"not" function
for(var i=0;i<arr.length;i++) {
  if(arr[i] == dat){return false;}
}
return true;
}

var check = [2,3,4,5,6,7,8,9,18,19,49,50,60,61,70,78,79,80,81,82,90,91,92,93,94]; //numbers

if(not(i, check)) {
//do stuff
}

此解决方案是跨浏览器的:

var valid = true;
var cantbe = [3, 4, 5]; // Fill in all your values
for (var j in cantbe)
    if (typeof cantbe[j] === "number" && i == cantbe[j]){
        valid = false;
        break;
    }

valid true 如果 i 不是“坏”值, false 否则。