验证JavaScript函数的参数

一段简单代码，用于验证JavaScript函数中的参数个数，类型等

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使用方法：

在每个函数执行前调用验证函数，如果验证未通过，验证函数将返回true,否则返回false或者null

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String.__typeName = "string";Number.__typeName = "number";Array.__typeName = "array";Function.__typeName = "function";Object.__typeName = "object";ffap = {};ffap.Utils = {    _isInstanceOfType: function(type, instance){        if (type === String) {            return (typeof instance === "string");        }        if (type === Number) {            return (typeof instance === "number");        }        if (type === Boolean) {            return (typeof instance === "boolean");        }        return instance instanceof type;    },        /**     * 验证函数参数     *     * @param {Object} params待验证的参数     * @param {Object} expectedParams期望的参数     * @param {Object} validateParameterCount是否验证参数个数，默认为true     */    validateParams: function(params, expectedParams, validateParameterCount){        /* 待验证的参数个数 */        var expectedLength = expectedParams.length, error = false;        validateParameterCount = validateParameterCount !== false;                error = ffap.Utils._validateParameterCount(params, expectedParams, validateParameterCount);        if (error) {            return true;        }                for (var i = 0, l = params.length; i < l; i++) {            var expectedParam = expectedParams[Math.min(i, expectedLength - 1)], paramName = expectedParam.name;            if (expectedParam.parameterArray) {                paramName += "[" + (i - expectedLength + 1) + "]";            }            else                 if (!validateParameterCount && (i >= expectedLength)) {                    break;                }            error = ffap.Utils._validateParameter(params[i], expectedParam, paramName);            if (error) {                return error;            }        }        return false;    },            _validateParameterCount: function(params, expectedParams, validateParameterCount){        var i, error, expectedLen = expectedParams.length, actualLen = params.length;        if (actualLen < expectedLen) {            var minParams = expectedLen;            for (i = 0; i < expectedLen; i++) {                var param = expectedParams[i];                if (param.optional || param.parameterArray) {                    minParams--;                }            }            if (actualLen < minParams) {                error = true;            }        }        else             if (validateParameterCount && (actualLen > expectedLen)) {                error = true;                for (i = 0; i < expectedLen; i++) {                    if (expectedParams[i].parameterArray) {                        error = false;                        break;                    }                }            }        if (error) {            console.log("参数个数不正确");            return true;        }                return false;    },        _validateParameter: function(param, expectedParam, paramName){        var error, expectedType = expectedParam.type, expectedInteger = !!expectedParam.integer, expectedDomElement = !!expectedParam.domElement, mayBeNull = !!expectedParam.mayBeNull;                error = ffap.Utils._validateParameterType(param, expectedType, expectedInteger, expectedDomElement, mayBeNull, paramName);        if (error) {            return error;        }                var expectedElementType = expectedParam.elementType, elementMayBeNull = !!expectedParam.elementMayBeNull;                if (expectedType === Array && typeof(param) !== "undefined" && param !== null &&        (expectedElementType || !elementMayBeNull)) {            var expectedElementInteger = !!expectedParam.elementInteger, expectedElementDomElement = !!expectedParam.elementDomElement;            for (var i = 0; i < param.length; i++) {                var elem = param[i];                error = ffap.Utils._validateParameterType(elem, expectedElementType, expectedElementInteger, expectedElementDomElement, elementMayBeNull, paramName + "[" + i + "]");                if (error) {                    return error;                }            }        }                return false;    },        _validateParameterType: function(param, expectedType, expectedInteger, expectedDomElement, mayBeNull, paramName){        var error, i;                if (typeof(param) === "undefined") {            if (mayBeNull) {                return null;            }            else {                console.log("参数" + paramName + "不能为undefined");                return true;            }        }                if (param === null) {            if (mayBeNull) {                return null;            }            else {                console.log("参数" + paramName + "不能为null");                return true;            }        }                        if (expectedType && !ffap.Utils._isInstanceOfType(expectedType, param)) {            console.log("参数{" + paramName + ":" + param + "}的类型不匹配\n" + "应为：" + expectedType.__typeName + "\n实际为：" + typeof param);            return true;        }                if (expectedType === Number && expectedInteger) {            if ((param % 1) !== 0) {                console.log("参数{" + paramName + ":" + param + "}不是整数");                return true;            }        }                return false;    }};

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使用：

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function func(a, b, c){    var error = ffap.Utils.validateParams(arguments, [{        name: "a",        type: Array,        mayBeNull: false,        optional: true,                elementType: Number,        elementMayBeNull: false    }, {        name: "b",        type: Boolean,        mayBeNull: false,        optional: false    }, {        name: "c",        type: Number,        mayBeNull: false,        optional: false    }]);        if (error) {        return;    }        执行原来其他函数体...}

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参数描述见下表：

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属性

描述

type

期望的参数类型。可取值包括String、Number、 ? Boolean、Array、Function和Object

mayBeNull

如果为true，参数可以为null

optional

如果为true，参数可以忽略

integer

如果参数是一个Number，指定是否必须为整数

elementType

如果参数是一个Array，指定其元素的期望类型，

可取值与type属性相同

elementMayBeNull

如果参数是一个Array，指定是否可以包含null元素

elementInteger

如果参数是一个Array，指定其元素是否为整数

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其中错误信息使用的是FireBug的console打印