Digital:function isNumber(val){if((typeof(val)==‘number‘)||(val instanceof Number)){ return true}else{ return false}}
String:function isString(val){if((typeof(val)==‘string‘)||(val instanceof String)){ return true}else{ return false}}
Boolean value:function isBoolean(val){if((typeof(val)==‘boolean‘)||(val instanceof Boolean)){ return true}else{ return false}}
Array:function isArray(val){if(val instanceof Array){ return true}else{ return false}}
Test:
A. Code:var a = new Number(1)var b = new String(‘a‘)var c = new Boolean(true)var d = new Array(1,2,3)var e = 1var f = ‘f‘var g = falsevar h = [1,2,3]function isNumber(val){if((typeof(val)==‘number‘)||(val instanceof Number)){ return true}else{ return false}}function isString(val){if((typeof(val)==‘string‘)||(val instanceof String)){ return true}else{ return false}}function isBoolean(val){if((typeof(val)==‘boolean‘)||(val instanceof Boolean)){ return true}else{ return false}}function isArray(val){if(val instanceof Array){ return true}else{ return false}}console.log(isNumber(a))console.log(isString(b))console.log(isBoolean(c))console.log(isArray(d))console.log(isNumber(e))console.log(isString(f))console.log(isBoolean(g))console.log(isArray(h))
B. Output:
truetruetruetruetruetruetruetrue
JavaScript Judging data types