if($.isArray(arrayList))console.log('数组'); 别的console.log('不是数组'); 仅供参考要确定一个对象是否是一个数组,jQuery 在内部使用 Object.prototype.toString.call 方法。 您还可以使用现代浏览器来: Array.isArray(arrayList); Array.is Chrome 5、Firefox 4.0、Internet Explorer 9、Opera 10.5 和 Sa...
判断时使用Object.prototype.toString.call( list )==='[object Array]'或者Object.prototype.toString.call( list )=='[object Array]',==或者===一样的效果。 测试3: 如果使用jquery,可以使用$.isArray(obj)的方法,如下: vara = ["A", "AA", "AAA"];if($.isArray(a)) { console.log("a is ...
通过测试,使用如:obj instanceof Object的形式,只能是判断两种类型Object和Array,其中Boolean、Number、String可以判断,但是会返回false,如上面i和b变量;如果判断为null或者undefind会报Uncaught TypeError: Right-hand side of 'instanceof' is not an object这样的错误。 测试5: 直接通过Array.isArray(obj),javascri...
// function return if an element is found in the array, else falsefunctioncheckTrueExistsArray(array) {for(vark=0;k<array.length;k++) {if(array[k]) {returntrue;break;}}returnfalse;}vararrayVariable=[false,false,true,false,true];vararrayVariable1=[false,false,false,false,false];console....
Checks if value is classified as an Array object. constarray=['🍝','🍜','🍲'];constnotArray='not array';_.isArray(array);// true_.isArray(notArray);// false Underscore Returns true if object is an Array. constarray=['🍝','🍜','🍲'];constnotArray='not array';_.isArr...
If you don't want it to throw aTypeError, you can add an extra check: letvalue;value// 👈 null and undefined check&&Object.keys(value).length===0&&value.constructor===Object;value=null;// nullvalue=undefined;// undefined Perfect, no error is thrown 😁 ...
. Every Array object has alengthproperty whose value is always a nonnegative integer less than 2...
Add value if not exists Loop through the array to check whether a particular username value already exists and if it does do nothing, but if it doesn’t add a new object to the array. const arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 3,...
If a number is supplied, delay is applied to both hide/show Object structure is: delay: { show: 500, hide: 100 } container string | false false Appends the tooltip to a specific element container: 'body' 注意! 可以针对单个工具提示指定单独的data属性。 标记 <a href="#" data-toggle="...
function checkData() { if (document.form1.threeChar.value.length == 3) { return true; } else { alert("Enter exactly three characters. " + document.form1.threeChar.value + " is not valid."); return false; } } 「switch 语句节」switch 语句允许一个程序求一个表达式的值并且尝试去匹配表...