if (‘X’ in mmap) { // … } Here is an example on JSFiddle. hasOwnProperty is also valid, but using in is much more painless. The only difference is that in returns prototype properties, whereas hasOwnProperty does not.
Because arrays are mutable. The index of any given item can and will change if items are added to or removed from the array. You want your key to be a unique value identifying only your unique component. A primary key that you create is always better than using an index. Here is an example. … Read more
You can pass another parameter within your map function like so: this.state.elements.map((element, index) => { return <span style={element.myStyle} key={index} >{element}</span>; }); The second parameter of the Array.prototype.map function actually contains the current index of the particular element in that array. This way, you’ll be sure that your key is not duplicated.
You can use the ? to make the keys optional, so interface Partial { a?: boolean; b?: boolean; c?: boolean; } Or, you can do this: type Keys = “a” | “b” | “c”; type Test = { [K in Keys]?: boolean }
In java you don’t check if a key is pressed, instead you listen to KeyEvents. The right way to achieve your goal is to register a KeyEventDispatcher, and implement it to maintain the state of the desired key: import java.awt.KeyEventDispatcher; import java.awt.KeyboardFocusManager; import java.awt.event.KeyEvent; public class IsKeyPressed { private static volatile boolean wPressed = false; … Read more
Unless your jq has inputs, you will have to slurp the objects up using the -s flag. Then you’ll have to do a fair amount of manipulation: Each of the objects needs to be mapped out to key/value pairs Flatten the pairs to a single array Group up the pairs by key Map out each … Read more
you can also use Array.some() function: const arr = [ { id: 19, cost: 400, name: ‘Arkansas’, height: 198, weight: 35 }, { id: 21, cost: 250, name: ‘Blofeld’, height: 216, weight: 54 }, { id: 38, cost: 450, name: ‘Gollum’, height: 147, weight: 22 } ]; console.log(arr.some(item => item.name === ‘Blofeld’)); console.log(arr.some(item => item.name … Read more
The original tag for this question was jq so here is a jq solution: .[] | keys[] For example, with the input as shown in the question: $ jq ‘.[] | keys[]’ input.json “identifier1” “identifier2” To retrieve the key names in the order they appear in the JSON object, use keys_unsorted.
You can use any key if you use [string] to access the key, even key with space. All of these are valid: myObj[‘key with space’] myObj[‘12345’] But if you want to use dot . operator to access the key then the key must be a valid identifier which means they can not begin with a … Read more
For indexing columns that have Large sizes ,sqlserver indexes only columns that have size up to 900 bytes. To solve this problem Firstly : I added a column hashCol to generate hashcode of Type SHA1 for MyCol alter table myTable add hashCol AS HASHBYTES(‘SHA1’, CONVERT(VARCHAR(90), MyCol)) Secondly : I added a unique constrain for hashCol … Read more