js使用typeof與instanceof相結合編寫一個判斷常見變量類型的函數

/**
 * 常見類型判斷
 * @param {any} param 
 */
function getParamType(param) {
    // 先判斷是否能用typeof 直接判斷
    let types1 = ['number', 'string', 'boolean', 'undefined', 'symbol', 'function']
    let type = typeof param;
    type = types1.indexOf(type);
    if (type !== -1) {
        return types1[type]
    }
    // 剩餘的用instanceof判斷
    switch (true) {
        case param instanceof Date:
            return 'date'
        case param instanceof Array:
            return 'array'
        case param instanceof Object:
            return 'object'
        case null === param && !param:
            return 'null'    
        default:
            return 'can not judge'
    }
}


console.log(getParamType(1)); // number
console.log(getParamType('1')); // string
console.log(getParamType(true)); // boolean
console.log(getParamType(undefined)); // undefined
console.log(getParamType(Symbol.for(2))); // symbol
console.log(getParamType(() => 1)); // function
console.log(getParamType([])); // array
console.log(getParamType({})); // object
console.log(getParamType(new Date())); // date
console.log(getParamType(null)); // null
           

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