Example 1
| The code is as follows |
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if (Tt==null | | tt== "") {
Alert ("Kong");
} else {
Alert ("Bukong");
} |
Example 2
| The code is as follows |
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The var is = function (Obj,type) {
return (type = = "Null" && obj = = null) | |
(Type = = "Undefined" && obj = = void 0) | |
(Type = = "Number" && isfinite (obj)) | |
Object.prototype.toString.call (obj). Slice (8,-1) = = type;
} |
Whether an element of an array is empty
1. If an array element does not exist: if (arr[x] = = undefined) determines
2. If the content in the element is null, it needs to be judged by the value of the array you are populating.
| code is as follows |
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| var B = new Array (1,null, ')
Console.log (b[1] = null);//fill element with null value
Console.log (b[2] = = ");//Fill element with empty (') value
Console.log (b[3] = = undefined); To determine an element that does not exist |
