From the documentation JSLint also recognizes a /*global */ directive that can indicate to JSLint that variables used in this file were defined in other files. The comment can contain a comma separated list of names. Each name can optionally be followed by a colon and either true or false, true indicating that the variable … Read more
I am a fan of always including null explicitly as that carries meaning. While omitting a property leaves ambiguity. As long as your protocol with the server is agreed upon any of the above can work, but if you pass nulls from the server I believe that makes your APIs more flexible later. Should also … Read more
response[0] is not defined, check if it is defined and then check for its property title. if(typeof response[0] !== ‘undefined’ && typeof response[0].title !== ‘undefined’){ //Do something }
Yes, it can do that, but strictly speaking that will assign the default value if the retrieved value is falsey, as opposed to truly undefined. It would therefore not only match undefined but also null, false, 0, NaN, “” (but not “0”). If you want to set to default only if the variable is strictly … Read more
I’m a bit confused about Javascript undefined & null. null generally behaves similarly to other scripting languages’ concepts of the out-of-band ‘null’, ‘nil’ or ‘None’ objects. undefined, on the other hand, is a weird JavaScript quirk. It’s a singleton object that represents out-of-band values, essentially a second similar-but-different null. It comes up: When you call … Read more
Try this var n1 = document.getElementById(‘editor’).innerHTML; // or innerText, or textContent
If you want to return observables in a sequential manner, you shouldn’t nest your subscribe() methods. Instead, we should be using RxJS’s mergeMap to map over the observable values from the activatedRoute into an inner observable, which is assigned to the newsID property. Then, we call the getSectors() method from _newswireService, and the observables are … Read more
1. Is getA1() implementation correct ? I feel it is incorrect as it is returning address of local variable or temporary. The only version of getAx() that is correct in your program is getA3(). Both of the others have undefined behaviour no matter how you use them later. 2. Which of the statements in main … Read more
void has special meaning in function return types, and is not an alias for undefined. Thinking of it this way is very wrong. Why? The intent of void is that a function’s return value will not be observed. This is very different from will be undefined. It’s important to have this distinction so that you … Read more
The best way is to check the type, because undefined/null/false are a tricky thing in JS. So: if(typeof obj !== “undefined”) { // obj is a valid variable, do something here. } Note that typeof always returns a string, and doesn’t generate an error if the variable doesn’t exist at all.