// shallow clone/copy:
let arr2 = [].concat(arr1);
let arr3 = [...arr1];
let obj2 = Object.assign({}, obj1);
let obj3 = {...obj1};
// deep clone/copy
let obj2 = JSON.parse(JSON.stringify(obj1)); // old approach
let obj3 = structuredClone(obj1); // new approach
When using two equals signs for JavaScript equality testing, some funky conversions take place.
| {{ keys[index1] }} |
|
| {{key}} |
When using three equals signs for JavaScript equality testing, everything is as is. Nothing gets converted before being evaluated.
| {{ keys[index1] }} |
|
| {{key}} |
Note: This row does not match up with any of the rows in the other table.
| {{ key }} |
|
if ({{ key }}) { /* {{ values1[index] ? 'executes' : 'does not execute' }} */ } |
fetch(url)
.then(data => data.json())
.then(data => { console.log(data); })
.catch(error => alert(error));
| Original Value |
Converted to Number |
Converted to String |
Converted to Boolean |
|---|---|---|---|
| false | 0 | "false" | false |
| true | 1 | "true" | true |
| 0 | 0 | "0" | false |
| 1 | 1 | "1" | true |
| "0" | 0 | "0" | true |
| "000" | 0 | "000" | true |
| "1" | 1 | "1" | true |
| NaN | NaN | "NaN" | false |
| Infinity | Infinity | "Infinity" | true |
| -Infinity | -Infinity | "-Infinity" | true |
| "" | 0 | "" | false |
| "20" | 20 | "20" | true |
| "twenty" | NaN | "twenty" | true |
| [ ] | 0 | "" | true |
| [20] | 20 | "20" | true |
| [10,20] | NaN | "10,20" | true |
| ["twenty"] | NaN | "twenty" | true |
| ["ten","twenty"] | NaN | "ten,twenty" | true |
| function(){} | NaN | "function(){}" | true |
| { } | NaN | "[object Object]" | true |
| null | 0 | "null" | false |
| undefined | NaN | "undefined" | false |