Scenario Analysis of JSON Merge with Practical Javascript Methods

Scene

2 json merge,

There are two prototypes of jQuery's "extend()" method: merging methods, namely shallow merge and deep merge. In fact, shallow merge is only the first layer of json being merged, while deep merge is that all layers are merged, respectively:

1. Shallow merge, target is merged by object1..., with only one layer

$.extend( target [, object1 ] [, objectN ] )

Deeply merged, target is merged by object1..., containing one, two, and three layers...

To deeply merge, [deep] needs to be true, with the back covering the front, so if you want to keep the back, you need object1 =$.extend(true,target,object1) , but the target has changed

$.extend( [deep ], target, object1 [, objectN ] )

This is from jquery. Let’s take you to see how JavaScript is implemented.

Code

1. Deep Merge (Recursion)

/**
 * When encountering the same element-level attribute, the (minor) shall prevail. // No new Object is returned, but the main change is
 * mirror
 * main
 */
function mergeJSON(minor, main) {
    for(var key in minor) {
        if(main[key] === undefined) { // If there is no conflict, directly assign value            main[key] = minor[key];
            continue;
        }
        // Conflict. If it is an Object, see if there are any attributes that do not conflict        // If it is not an Object, the (minor) shall prevail.        //(key)
        if(isJSON(minor[key])||isArray(minor[key])) { // Recursively called and decoupled from the function name            ("is json")
            //(minor[key], main[key]);
            mergeJSON(minor[key], main[key]);
        }else{
            main[key] = minor[key];
        }
    }
}    
//Judge whether it is jsonfunction isJSON(target) {
    return typeof target == "object" &amp;&amp;  == Object;
}
//Judge whether it is an arrayfunction isArray(o) {
    return (o) == '[object Array]';
}

test

var a = {
    ccc: {
        d: 111,
        b: 222,
        a: 222,
        ee: [{
            a: 1
        }, {
            b: 2
        }]
    }
};
var b = {
    ccc: {
        fff: 666,
        ee: [{
            c: 3
        }]
    }
};
mergeJSON(b, a);
(a);
(b);

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