var arr =[ {name:'zhangsan'}, {name:'lisi'}, {name:'wangwu'} ]; var json1 = {name:"zhangsan"}; // 方法一:(兼容ie8) console.log(JSON.stringify(arr).indexOf(JSON.stringify(json1))); // 方法二: (前提是匹配和被匹配的存在赋值关系) var json2 = arr[0]; var json3 = {name:'zhangsan'}; console.log('json2',arr.indexOf(json2)); // 存在 console.log('json3',arr.indexOf(json3)); //不存在
underscore 中isEqual的源码;
// Internal recursive comparison function for `isEqual`. var eq = function(a, b, aStack, bStack) { // Identical objects are equal. `0 === -0`, but they aren't identical. // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal). if (a === b) return a !== 0 || 1 / a === 1 / b; // A strict comparison is necessary because `null == undefined`. if (a == null || b == null) return a === b; // Unwrap any wrapped objects. if (a instanceof _) a = a._wrapped; if (b instanceof _) b = b._wrapped; // Compare `[[Class]]` names. var className = toString.call(a); if (className !== toString.call(b)) return false; switch (className) { // Strings, numbers, regular expressions, dates, and booleans are compared by value. case '[object RegExp]': // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i') case '[object String]': // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is // equivalent to `new String("5")`. return '' + a === '' + b; case '[object Number]': // `NaN`s are equivalent, but non-reflexive. // Object(NaN) is equivalent to NaN if (+a !== +a) return +b !== +b; // An `egal` comparison is performed for other numeric values. return +a === 0 ? 1 / +a === 1 / b : +a === +b; case '[object Date]': case '[object Boolean]': // Coerce dates and booleans to numeric primitive values. Dates are compared by their // millisecond representations. Note that invalid dates with millisecond representations // of `NaN` are not equivalent. return +a === +b; } if (typeof a != 'object' || typeof b != 'object') return false; // Assume equality for cyclic structures. The algorithm for detecting cyclic // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`. var length = aStack.length; while (length--) { // Linear search. Performance is inversely proportional to the number of // unique nested structures. if (aStack[length] === a) return bStack[length] === b; } // Objects with different constructors are not equivalent, but `Object`s // from different frames are. var aCtor = a.constructor, bCtor = b.constructor; if ( aCtor !== bCtor && // Handle Object.create(x) cases 'constructor' in a && 'constructor' in b && !(_.isFunction(aCtor) && aCtor instanceof aCtor && _.isFunction(bCtor) && bCtor instanceof bCtor) ) { return false; } // Add the first object to the stack of traversed objects. aStack.push(a); bStack.push(b); var size, result; // Recursively compare objects and arrays. if (className === '[object Array]') { // Compare array lengths to determine if a deep comparison is necessary. size = a.length; result = size === b.length; if (result) { // Deep compare the contents, ignoring non-numeric properties. while (size--) { if (!(result = eq(a[size], b[size], aStack, bStack))) break; } } } else { // Deep compare objects. var keys = _.keys(a), key; size = keys.length; // Ensure that both objects contain the same number of properties before comparing deep equality. result = _.keys(b).length === size; if (result) { while (size--) { // Deep compare each member key = keys[size]; if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break; } } } // Remove the first object from the stack of traversed objects. aStack.pop(); bStack.pop(); return result; }; // Perform a deep comparison to check if two objects are equal. _.isEqual = function(a, b) { return eq(a, b, [], []); };