在遍历字典的过程当中,我们可以用以下状态图来展示常见的流程: StartIterateCheckKeyExistsPrintValueEnd 解释状态图 Start:开始遍历字典。 Iterate:进入遍历状态。 CheckKeyExists:检查当前键是否存在。 PrintValue:打印出当前键对应的值。 End:遍历完成,结束。 字典的应用场景 字典在日常编程中有多种应用场景: 存储用户...
Checking Whether a Property Exists You can check whether an object has a property, or whether a property exists directly inside an object: propKey in obj Returns true if obj has a property whose key is propKey. Inherited properties are included in this test. Object.prototype.hasOwnProperty...
constarr=[1,2,3,4,5];// Check if there is the number 3 in the arrayarr.include(3);// trueif(arr.include(3)){...}// ... Equivalent to the previous writing of indexOfarr.indexOf(3);// 2 (return its array position)// If you want to write it in the if, you must add ...
// sample script to delete a pair of key-value properties, sq3 and sa3, from object 'oVendors'dsFld =getField("dataSrc");oVendors = JSON.parse(dsFld.value);for(var key in oVendors){if (oVendors[key].hasOwnProperty('sq3'))//check if prop existsdelete.oVendors[key]['sq3'];...
save(function(err) { if (err) done(err); else done(); }); }); }); }); Alternatively, just use the done() callback directly (which will handle an error argument, if it exists): describe('User', function() { describe('#save()', function() { it('should save without error'...
{ // Get the element from the weak reference, if it still exists const element = this.ref.deref(); if (element) { element.textContent = ++this.count; } else { // The element doesn't exist anymore console.log("The element is gone."); this.stop(); this.ref = null; } }; tick...
(1) look uptimetocheckif the element existsinthe hash// If it does exist,addthat elementtothe new array.var hashmap = {};var intersectionArray = [];firstArray.forEach(function(element) {hashmap[element] = 1;});// Since weonlywanttopushuniqueelementsinourcase... we can implement a ...
createDirIfNotExists('test'); 3.currentURL:返回当前链接url const currentURL = () => window.location.href; currentURL(); // 'https://juejin.im' 4.distance:返回两点间的距离 该代码段通过计算欧几里得距离来返回两点之间的距离。 const distance = (x0, y0, x1, y1) => Math.hypot(x1 - x0...
function checkePlugs(pluginname) { var f = "-" var plugins = navigator.plugins; if (plugins.length > 0) { for (i = 0; i < navigator.pluginslength; i++) { if (navigatorplugins[i].name.indexOf(plugin) >= 0) { f = navigator.plugins[i.descriptionsplit(pluginname)[1...
Note that such a token always exists: if a comment appears at the end of a file, its following token is an EOFToken. As an example of a query using only lexical information, consider the following query for finding HTML comments, which are not a standard ECMAScript feature and should be...